DBPro Has a few niggles, But It's constantly being updated and given new command sets. By all accounts, the next update is going to be a biggie. Personally, I've never come accross a bug that's been a brick wall.
As for collision, I've never had any problems with it. The full polygon collision is a bit inaccurate but there are commands that let you write your own collision routines without too much fuss.
The biggest problem with DBPro is the lack of 3rd party support for the .x file format. It's quite difficult to find a decent modelling package with all of the features you may want that doesn't cost the earth. Some suggestions are:
JTEdit: Very comprehensive and free, but still under development
Milkshape: Comprehensive, well established, but a bit awkward $25/£17
Gamespace: professional package by caligari $299
There are various .x exporter plugins for 3ds MAX (if you're lucky enough to have access to it) which vary in quality depending on which version of max you use.
Above all, I've learned a lot from DBPro, and enjoyed every step, it cost me £50 from amazon and was worth every penny! Go on, you know you want to.
Strings are PChars ??????? What a World