I think that pretty much everything from Neftali's AA debut has been covered by someone, but to summarize, he is basically as advertised. He could probably survive in a pen right now, just based on his fastball, but to be an effective starter, he has a ways still to go. He has no faith in his breaking ball, at least at the new level, and it hurt him as he struggled through his last trip through the order and some fatigue (he only threw 80 pitches, but I think that he was pitching on adrenaline early and ran out of gas quickly as a result). He needs to improve his secondary pitches, but at this point, he just has to accept that he has to throw them, and that seems to make AA a good level for him right now.
Besides making the usual wish for good health for a pitching prospect, you just have to hope that the Rangers are able to finish off his development. From a basic standpoint, he has workable command of his fastball, and from reports ordinarily has better movement on it than he showed last night (possible trade-off for the extra velocity, and as everyone else has said, all guns did have him at 100 and 101 a couple of times). But he has pretty dramatic improvements to make on his second and third pitches. The change is no more than a "keep in mind, I may not throw it as hard" pitch at this point, but I think that the breaking ball is the key. As the scouts sitting behind home plate were noting, on the occasion that he did throw it, it was a mid-70's pitch with a little sharpness. Against his nasty fastball, that's the weapon that would give advanced hitters fits.
He's in AA, but I could see the timetable being anywhere from about four baseball months to as much as two years before he's truly ready. Hopefully he'll have a full arsenal of weapons by that time.
(sorry for the fuzziness, had completely the wrong lens with me by accident)