It's hugely overpopulated for the size that it is. The cost of living is absurdly high because of this. On the rare occasion that I'll venture into the area to go hiking you can't expect more than 30 seconds on a trail without encountering at least one large group of people coming towards you. The bike lanes, which are fucking everywhere, have been implemented at a pretty huge expense to the driving lanes.
Basically, the best way to experience Boulder is to not live there and not drive there. Going up there a few times a year to hike while avoiding the city entirely is the best Boulder experience one can have.