He does seem pretty uber. I kinda hate that about post-ROTJ EU material... Too much movie fixation. Han becomes uber, Boba becomes uber, the MF becomes uber, every Skywalker is a Forcegod/sabergod/etc.
But I imagine people ***** about pre-PT EU too as well. I dunno. I seem to find it easier to accept.
Luke only becomes uber in the last week of NJO. Jacen is uber on two differnet occasions, once in Traitor when wearing an armor of Amphistaffs and for a minute at the end of NJO. Jaina is definately NOT uber. Leia gets okay in Dark Nest. Han just kills people(DE Sidious for example) but never really fights. The Falcon does get uber, but only half of the time, the other half it is always about to blow up.
Really though, Jacen is the second most powerful Skywalker, and in NJO he is a fair bit less than Dooku or Mace.
Remember though that the Skywalker family is called the Lead Clan in the Galaxy by the Vong, so they have to be good.
I think you are going to have post-NJO even more, though. Ben Skywalker shoves a Jedi Knight across the room with an untrained force push and Jacen's daughter is supposed to be really powerful.