meh
exclamation
1.
expressing a lack of interest or enthusiasm.
"Meh. I'm not impressed so far"
adjective
1.
uninspiring; unexceptional.
"a lot of his movies are … meh"

vap·id
adjective
offering nothing that is stimulating or challenging.
"tuneful but vapid musical comedies"
synonyms: insipid, uninspired, colorless, uninteresting, feeble, flat, dull, boring, tedious, tired, unexciting, uninspiring, unimaginative, uninvolving, lifeless, tame, vacuous, bland, trite, jejune

Hmm...those words are practically interchangeable.