Depend on what you use it for and what is your aim. It can be quite effective (depend on the ship design) and make orbital rendez-vous trivial if you use it as a robot. If you want to play manually it can provide a lot of interesting data (delta-V, apoapsis, periapsis, true altitude, vertical velocity etc) allowing to fine tune your ships and missions. MechJeb only remove challenge ... if you want it to.