The tech demo comment is used ad nauseum in Crysis threads by people that don't like the games. It's practically a meme this point, and people routinely use it to just troll the games without providing any substantive thought. Sorry to jump on you specifically like that, but I guess I don't see how the series is anything like a tech demo. I can see how people might have trouble finding fun in a game that leaves you to move through it at your own pace, but that's a totally different discussion.
I hate to be that guy, but are Far Cry 3 and Crysis 3 really comparable? They're both shooters, but they aim for distinctly different experiences.