As I've recently made the leap from Quickbooks 5.0 to Quickbooks Pro 2008 (and blogged about it), I thought I would share my insights.
Likes
1) Conversion of my stone age database file (i.e. 5.0) was painless.
2) The user interface is remarkably similar to what I used to have.
3) Nice that they included a number of interactive demos (using Macromedia Flash) about how to use certain features.
4) My invoices are darker, so they're easier to read.
Dislikes
1) Startup speed is abysmal. Tips anyone?
2) Update process is never ending, it appears, and updates take a long time as well. Think two a week. If you update one computer but not another (a common scenario is any enterprise), then open a shared database, it displays a warning (potentially scaring non IT staff....nice).
3) Turning off all beeps and sounds took me three tries to squash them all. There are two settings, the help provides one clue when searching for "sounds" and another clue when searching for "beeps".