If you refer to this Qt3 games podcast, I think you’ll find @tomchick likes it just fine and sold @Vesper on taking the leap too. Not sure whether Vesper also plays it solo, but it’s meant to be very good that way.
This is the kind of podcast that makes me a bit sad though. Having to invest hundreds of dollars to get a cool game is not a viable way to stay in the hobby for me. So I had to pass.
My wife and I did splurge on Gloomhaven (still much cheaper) which provides 70+ hours out of the box. Judging by the Shut Up and Sit Down review of Too Many Bones and what I recall of Tom’s comments in the podcast, I think just the base game of Too Many Bones would get stale quicker than that.
Like Quinns said though, TMB is a game you buy to treat yourself. It might well be worth it for you.