I used to really enjoy J. J. Abrams, back when Alias was first getting started. But the way Sydney could travel 20,000 air-miles and have four pitched fights in the space of a weekend while being fresh as a daisy for her seminar on monday a.m., along with the shamless Maguffinism (can anybody say what all that mystical stuff was ever actually about, anyway?) soured me on it by sometime in the 2nd season. (Plus, how do you just *move* an entire EEEEEVIL terrorist spy organization into the CIA whole-hog?)
I gave Lost two solid seasons and just lost interest in the third, for similar reasons.
My general conclusion about Abrams has been that there's not much there, there. He's in it for the chase, and just about everything else is maguffin: relationships, technology, characters, you name it, they're all just excuses for situations, preferably involving either metaphorical or literal combat. (I long ago reached similar conclusions about David E. Kelley: that he was more than willing to sacrifice character-realism for an exciting plot development. And having said that I'll dial back on Abrams a little bit on character, and concede that [unlike kelley] when he changes up a character he usually finds some kind of force majeur to explain it away.)
So while I'm not very invested in Star Wars, I sympathize with Wars fans who are worried about what Abrams will do to their world. The cinematic SW universe is fragile and doesn't make a lot of sense, but Wars fans and Extended Universe (term?) writers have worked hard to shore it up; I can readily envision abrams waltzing in and recycling a faster-paced, sexier pastiche of Ep. 4-6 tropes with a little Extended Universe stuff thrown in to get the fanbase on board with promotions.