I'd say I mainly like it because of the pace. Never a boring week, ever. Well, and Lelouch is a pretty good break from the standard teenage ace pilot mold, a tactical genius who still suffers from being a complete idiot teenager and a weakling.
oh, and it's got Norio Wakamoto, always a plus.
The mech designs are interesting, The character personalities are well defined despite the large cast, the action is well choreographed and isn't just robot fighting, the plot so far has done a good job of defining the characters and putting forward a mystery over what the psychic powers are all about, the only real negative I see is that suspension of disbelief has to be turned up all the way, since Murphy's Law basically fucks with Lelouch all the fucking time. Still, the role of coincidence is no more than any other tragedy really.
All and all exactly what I'm looking for in an anime: a more or less well executed story done in broad strokes.