I am cautiously optimistic about this right now. Frankly, I really do not see how Disney could ruin Star Wars any worse then Lucas already has. The prequels ended up being mostly crap partially due to his desire to tell a fairly complex story that he didn't really know how to write, and partially because all he truly wanted out of them was an excuse to make a shit-ton of new toys. The fact of the matter is that Star Wars as a franchise, while magical in the beginning, has been primarily about selling toys at least since ROTJ, and possibly even earlier. The saga has become so cheapened at this point, it almost doesn't matter what they do with it. As much as I love some parts of the extended universe, (the Thrawn Trilogy and most of the X-Wing novels/comics/games) there was a lot of shit in there too (Young/Junior Jedi Knights, almost everything written by Kevin J Anderson, most of the New Jedi Order, and pretty much everything in the Clone Wars sub-franchise), and at this point it is so bloated and self-contradictory, I wouldn't really be all too sad if it were abandoned.
Considering how well Disney has handled Pixar and Marvel the last few years (and I also really liked Tron: Legacy), I would not be surprised at all if some good comes out of this. Maybe we will see the original, unaltered trilogy finally get a proper DVD/Blu-Ray release. Maybe Disney will take some cues from the fans and turn the Thrawn trilogy into the next films. Of course, it could all become a massive clusterfuck, but honestly, considering the state Lucas has left the Star Wars saga in, I doubt I could possibly be disappointed by comparison with anything Disney does to the franchise.