I think he will be good for power, but there a couple of things that would make me leery about having him as a fantasy OF starter in mixed leagues or leagues that are not deep:
1) His BA has always been decidedly mediocre, including in the minors, even at such hitter's paradises as Las Vegas. It would not be out of the question for him to turn in an Adam Dunn type of second half, which is deadly to BA in roto. The .335 from the second half last year looks like a clear aberration.
2) His Home/Road splits and L/R splits make him most valuable in league formats that provide enough roster space for platoon player or two. I play in such a league, and I plan to use him against LHPs and maybe RHPs on the road. But at home against righties, you are basically dealing with a very mediocre output (which makes sense since he is RH and plays in a pitcher's park). I do not think the current H/R split will remain as acute all season, but it will still be there.
So if you can live with a .250-.275 BA to get 12-15 HRs the rest of the year, Ross may be your guy as a full-time player; otherwise, you will maximize value by platooning him.