A lot of it was overblown, but there are some legit criticisms. It was a little too samey (at least in the first two seasons) at a time when they really should have been more daring and more willing to break the mold. Though I think that a lot of the "problems" with ENT already existed in other Trek shows; for some reason people were more willing to overlook them in the earlier ones.
Oh, and people hated
the ship. Not just the design, but the name. Apparently no ships before TOS could have been called Enterprise
, and how dare TPTB think otherwise.