It is a good (I wouldn't say 'solid' as others have) start. It still crashes with great regularity, doesn't seem to be able to always use PubMed well to find document info, suffers from (acknowledged) redraw problems.

I have several thousand papers in PDF living in a DevonThink database that I would love to be able to better organize with something like Papers.

However, not everything I have is PubMed-able, so other search engine plugins might be nice (DOI resolver maybe?)

My only main complaint is that this clearly alpha-version (remember back when 'beta' and 'public preview' meant 'feature complete'?) has the gall to be time-limited. I can understand the authors' desire / need for some funding for the project, but why not do something more positive, like provide early-adopters (i.e. alpha and beta testers) a price break on the eventual product, or the ability to buy in early for a reduced price.

I'm not comfortable putting enough of my database into the program to really 'test' it, since it is crashy, and paying for it in this mode is sort of out of the question.

On the plus side, however, is that it looks really promising. No one is forcing me to use it in its current form, so I'm just hoping for it to get a little better.