I like MechJeb because you can use it when you want, and not use it when you don't want to. I love hand flying my own launches and training to nail trajectories and maneuver nodes and such. But when I was playing RemoteTech in .90 and had to launch a bunch of cam sats, it was nice to be able to just just auto launch a few of them, since it started to get tedious. If I only want flight/craft info, I actually prefer Kerbal Engineer. One thing that was a bit disconcerting in a way was that, in 1.0, apparently ALL of the mechjeb abilities seem to be available right away and I've only got the first couple notes unlocked. Not sure if that is temporary or what. I always like the MechJeb progression. You are rewarded with less tedium as you advance.