Because I am a little bit obsessive, I wound up getting both the DS and PSP versions of Puzzle Quest.  Now I have characters in the low teens on each, because I just can't decide which is the proper "canonical" version.

On the surface, it would certainly appear to be the PSP version.  Much cleaner, brighter, and well laid out display.  By comparison the DS version feels cramped and poorly thought out.  Furthermore the DS (for reasons that are unclear to me) only allows touch input, rather than the much more precise and comfortable d-pad entry, which would be entirely suitable for a game like this.

But then, there are the bugs.  The PSP version is plagued with them, most notably that one entire game feature (Companions) simply doesn't work.  At all.  Much to my sadness, that's not the only problem, the real showstopped I'm having is that it hard-hangs the PSP when I scroll down through my list of abilities once it grows in size, and this is more or less a necessary UI feature. 

I thought the point of fixed hardware platforms like this was that they can be QA'ed much more thoroughly.  I guess someone forgot to tell Vicious Cycle and Infinite Interactive.  So it looks like the DS version will be the winner in the end.

No matter which version you get though, I highly recommend this game.  Penny Arcade's comic today is not far off the mark:

http://www.penny-arcade.com/comic/2007/03/26