I honestly believe that Lucas is in love with the art of special effects,and characterization and plot are secondary.
When episode IV came out,the time was right and the fx blew everyone away and was entertaining enough to work.
I don't think (and this is just my opinion) that he's a director that can produce a lot of depth in his movies. I thought American Graffitti was fun,but a whole of fluff. It mainly appeals to people's sense of nostalgia. But beneath the surface,there's not a whole lot there.
I really don't think Abrams can screw up the Star Wars legacy,especially after the debacle of the prequels. Will it have the magic of Episode IV? Most likely not,cause it's not 1977.