I just got finished upgrading my work computer to Snow Leopard and configuring everything. Here are my thoughts.

Installation
Typical painless Apple installation. It took somewhere between 30 mins and an hour; I'm not exactly sure since I was messing around with my synthesizers while it was running. Xcode has to be upgraded separately, and takes about ten minutes. After you install, Time Machine will re-backup all the differences between your old OS and your new one, and Spotlight will re-index various bits as you set them up (such as your email) - both these tasks happen in the background as usual.

Mail
Mail will upgrade all your email databases when you start it. I have a buttload of email, and it only took about a minute to convert all my databases (both work and personal email).

After I was done, I set up my Exchange account, which was previously accessed through IMAP. I put in a few basic details (email address, password, etc.) and Mail figured out the rest, including who our Exchange provider is - pretty impressive. It also auto-configured iCal and Address Book. The only hiccup I ran in to is that during auto-config of the Exchange account, since our email addresses differ from our usernames at Highwinds, Mail prompted me for my username.

After that, all my email got downloaded in to the new account. I reconfigured my Smart Mailbox filters to use the new account folders, and that was that.

iCal
When I opened iCal, I had two new calendars already set up for my Exchange calendar and tasks. Something that they fixed in the new iCal is that you can move an event from a Mac-local calendar to a shared calendar; I was not able to do this with the previous version of iCal when we used to use the Kerio server at Highwinds (an Exchange knock-off with Mac compatibility).

Moving tasks is mostly painless. Exchange doesn't have a priority of "none" so I changed all my tasks to be Medium priority to avoid iCal putting a little note in the task indicating that the priority could not be set. Exchange also doesn't support URLs like iCal does, so anything unsupported just gets moved in to the Notes area on the task. I also downloaded IMLite from the App Store, which lets me view my tasks (since Apple hasn't put that feature in the iPhone yet for some reason).

One thing I absolutely hate about the new iCal is the window that pops up to edit events and todos. In previous iCal versions, this was almost as bad, but at least workable. In the new version, the window always pops up to the top left corner of the screen, and does not act as an inspector - meaning that when you select new items, the window does not update to show the details of the new items; what happens instead is that each item gets its own pop-up window. If you move the window, it doesn't respect your new location, and continues to pop up in the top left, and multiple windows lay themselves out.

Seriously, WTF? With all Apple's UI expertise, they still can't get this right?

Apple, here is how iCal should let you edit events: put a pinnable inspector window somewhere in the app, just like the Tasks view or the mini-months calendar or anything else. As I select objects in the calendar, auto-save changes to the previous object and change the inspector's binding to show the settings for the newly selected object. Put up/down or previous/next arrows in it so I can scroll through all my to-dos or calendar events in sequence and set their properties. Allow me to select multiple items and make the inspector reduce its scope of editable items to only the common elements (i.e. associated calendar, date, etc.). Basically, what you did in iTunes with the song inspector, just with a pinnable window instead of a pop-up.

UPDATE: Either I am a douchebag, or Apple fixed this super-fast, or both. Guess what you can find in iCal's Edit menu? Nothing other than a "Show Inspector" option. And it's a nice one, too - always on top and stays where you put it. Damn you fruity bastards at Apple - you are good. :)

Address Book
Unsurprisingly, all my Exchange contacts showed up in my Address Book under a new heading. My Exchange directory was still there from before. Nothing fancy here, but nice that it all worked as expected and was auto-configured for me by the OS.

32-bit vs. 64-bit and Rosetta
Leopard will install by default in a 32-bit compatible mode, and run apps in either 32-bit or 64-bit mode automatically based on what the app supports. All the Apple core apps have been rewritten in 64-bit from what I understand, including Finder, Mail, iCal, Safari, System Preferences, and the other staples.

Device drivers must be 64-bit. Some drivers will not work in Snow Leopard due to the 64-bit requirement. The only two drivers I have personally had issues with are my open-source USB rocket launcher driver (don't really need that to be honest) and the drivers for my Access Virus TI synth. Access is working on updating the drivers, so I'm just going to wait on upgrading my personal Mac until they have that sorted out since I like the "total integration" features that TI stands for.

The 32-bit support is really smart. If I try to open 32-bit preference panes in System Preferences (such as the MySQL or LockTight panes), System Preferences warns you that it needs to restart, and does so in 32-bit mode. You can explicitly tell an app to always start in 32-bit mode by selecting a checkbox in Finder's Get Info pane for that application.

Rosetta is not installed by default. I fired up Quicken 2002 Deluxe and Snow Leopard asked me if it should install Rosetta, which it did by downloading the software from the web. Rosetta is also on your Snow Leopard installation disk if you want to include it by default. Quicken ran just as well in Rosetta on Snow Leopard as it did in previous versions of OS X.

I had mixed results on two OS plugins that I use regularly: MenuMeters didn't work (although a fix is in the works as of the August 17th blog post ), and Quicksilver runs just fine. Keyboard shortcuts in TextMate for jumping to the beginning and end of the line using Apple-[left/right] arrow stopped working, but somebody published a patch and this will be fixed in the next minor release according to the ticket.

Is It Faster? Better?
Yeah, in different ways. Safari has finally hit its stride with blazing performance, and I like the Google Suggest integrated in to the search widget. Finder is a lot snappier in certain operations, like opening a stack full of downloads. Expose is so fast it seems to twitch in to view compared to before, and I really like the even sizing of the windows - much easier to read (and now I understand at least one reason why they wanted resolution-independent graphics technology in OS X). Expose also allows you to zoom in on Expose'd windows by hovering with your mouse and hitting space bar, giving you a Quick View-style pop-up - a nice touch. The new Dock menus are smoky-black like the stacks are in Leopard, so that is more consistent. Windows are now apparently spring-loaded for dragging files between them, which I am sure I will use since I have been known to love me some spring-load.

There are some other cool features in it that I haven't touched yet. I haven't tried the new QuickTime X, but I can see myself taking little video notes with it now that it supports basic web cam capture and editing features; no need to fire up iMovie any more. I cursed Preview just yesterday for is lack of column-based PDF text selection, and that is in there now. And if you use any of your computers as a file server, Snow Leopard lets you put them to sleep and still advertise their files if you have a compatible Time Capsule or Airport Extreme base station - when you want the files from a remote computer, it wakes the computer with the files up, and then puts it back to sleep. Unfortunately, my main file server is an old G4 tower that is too long in the sabre tooth (hah!) for Snow Leopard, but I house my iTunes library on my personal laptop so I can see myself using this feature there.

Conclusions
Honestly, I wouldn't say you should rush out and buy Snow Leopard if you're on Leopard already, but I think it's definitely worth $29 (or $49 for the family pack, which I bought). The speed difference is evident, but besides that it's much the same as Leopard. The main thing I bought Snow Leopard for was Exchange support, and I got far more than my money's worth out of that feature alone.