Sure some folks have anecdotes about a poor local branch. You get out what you put in I think. If you want more interesting local meetings, then perhaps volunteer to find a speaker or event? Or even speak yourself?
Mensa members are smart, sure. But what does that mean? I once bought a book of 'Mensa puzzles' published by the organization (by Dr. Salny anyway, their national head). I went through it from end to end, and figured out most of the puzzles. They ranged from wordplay to story problems to logical reasoning and on and on. In the back were the solutions, and the percentage of Mensa members tested that got them right.
This was the most interesting part. For the math and arithmetic problems, from 10% to 25% of Mensa members got them wrong. How could that be right? Well, because (tested) intelligence isn't just about math. It ranges all over the map.
And so do Mensa members. They have curiosity about the whole range of the human condition. And (good) member meetings are all about that - discussing and enlightening and disputing things, to a deeper level perhaps than folks normally get at a family dinner or meetup at a bar.
Anyway for what it's worth the discussion here is more interesting for folks' reaction to Mensa, than for any real insight into what Mensa is about.