As a ranger fan who has followed his every move...
Hes not a fantasy player right now. He will start and it will be on opening day (they've said they do not want to "play games" with his eligibility since its a bad relationship starter with the player), but hes not ready as a hitter and while he won't be sent down too quickly he could at least lose some starts to vizquel.
But beyond on all that, he is not likely to get on base enough to steal enough bases to be mixed league fantasy relevant, and while Im sure he will get to run quite a bit it should be considered that hes the 9 spot in front of Ian Kinsler... first base should be scoring position with kinslers barrage of XBH.
I expect him to develop over a few years into a fantasy player as he adds a little more pop and will likely hit for a good average eventually, but for 2009 I'm only expecting him to be someone you pick up in AL only leagues when hes on a hot streak.
So uh yeah.. in real baseball the defense (errors at 19 in AA, who cares) will help him contribute and I expect him to develop into a good player pretty quickly, but for 2009 fantasy I dont think so, at least until we see how often he runs. Id rather try to make a trade to gain some speed if you really need it.