I like both his writing ability and his guitar playing. Didn't have the chance to watch Finck live, only on youtube and bootlegs, but I couldn't feel his energy on stage. With DJ I feel like I'm watching him in person not on a screen every single time.
And btw, his work with Sixx:AM is awesome, and I can't wait to see what they came up with now, and really hope he'll have the chance to write something with GNR, cause his sensitivity with Axl's lyrics would be epic
Oh, and personality - he seems like the sweetest man, real fun to be around, easy going (this based on his interaction with fans and with me on a few ocasions)