I loved First Contact. Definitely the best of the TNG movies, but not quite my overall favourite.
It's a very good movie, but except for things like warpdrive, transporters and such, it lacks what it actually at the core of Star Trek; the moral dillema and exploration of humanity. Essentially, First Contact was a SciFi Action movie. And that's why it's populair.
I say Trek can be and has been a lot of things. That's the beauty of the format. Fun action-adventure is as much "true" Star Trek as the moral quandries and "exporation of humanity" are.