I liked this movie a lot more than I liked Star Trek III. Oh sure, i's not great, but the comedic bits had me XD!! more than once. It was a lot "under explained" than the TOS episodes though. The crew didn't even speculate what the big "energy face" was about, or even how they were suddenly able to cross the "great barrier."
Was the great barrier just something no one ever tried crossing before? "Oh man that looks dangerous."