I generally have 2 opinions. The pre-play opinion, based on videos, streams, blogs, previews etc and the after-play opinion, where I finally get to play and can get a judgement from that. I never expect games to provide years of entertainment. If after I play it either via beta, trial , etc and I find it enough to give initial investment of time/money, all I expect at that point is to get at least 50 or more hours out of the game. If it turns out to be a lot more and the game can keep me hooked for longer then all the better, but I never expect the latter.