The most fundamental issue with Logic 8 that is likely to affect VSL users is the arrange window. In 7 it presented a mini score where you could see all the notes, their position and to, some extent, their pitch. This incredibly useful tool has been removed.
You can no longer colour objects in the environment to help with complex large arrangement mixes.
You can no longer sample rate convert files in the sample edit window (where you could select parts of the file to work with)
Every time you click on a region in the arrange the bottom part of your window is obscured with a window opening - you cannot defeat this behaviour.
The compatibility of songs created in previous versions is somewhat buggy and incomplete in LP8 which anyone working on long running projects, or working on remixes, or having an archive will be concerned about.
I'm a long (very) term Logic user, and one of it's biggest fans and appreciate some of the new features but these come with the disadvantage of moving the application more towards a Garage Band style whilst removing facilities that were fundamental to some high level pro workflows.
Julian