What I did was buy the DBLite version for $15, and then ordered the upgrade to DBPro for $85. For a little extra trouble, you get the Lite version to use while you're waiting to receive Pro via mail.
DBLite has no watermark or nag screen when you exit - only the demos have those. DBLite can run any of the DB demos that don't use commands from or depend on features added by the Enhancement Pack. DBLite is not too shabby... you can do quite a lot with it.
DBPro has many more commands than DB or DBLite (so it is harder to learn), but it also has some really nice commands that make things a whole lot easier. Some notable examples are the SPRITE ROTATE and SPRITE MOVE commands. Tired of making sprites with 36 different pictures with your spaceship turned in different directions... just make one picture and let DBPro do the rotations. Tired of converting all of your 3DStudio models to .X format - Pro can load .3DS files directly with LOAD OBJECT.
DBPro is new, so there are problems with it, but as RPGamer said, they are actively working to improve DBPro all the time (but work on DB is finished). Also, lots of people still program with DB, and from what I can tell, converting DB programs to DBPro can be time-consuming, and may even involve some rewriting of your programs. I haven't had much luck with running DB programs in the DBPro Demo (but that may just be that the Demo is not fixed up enough compared to the full version of DBPro).
Anyway... hope this helps!
Ed
