Ashamed to say I played hours of the Bionic Commando reboot's multiplayer demo and quite enjoyed it in spite of the occasional lag (reasoning that the final game would have all that sorted). I mean, it was spiderman plus guns, or Gears plus webslinging, what's not to love? It took me about an hour with the final game to figure out that the campaign just wasn't worth playing, and the final multiplayer was somehow more broken than the demo.
Similar problem with Destiny. I played the hell out of the demo thinking, "Wow, the gunplay and bikes are fun. This is stupid repetitive, sure, but it's just a demo. I can't wait to explore the rest of the game." Lo and behold, that one rusty plane is all there is to earth, and the other maps are just as puny. Worse, the only differences between them were visual. I get that it's not a simulation, but how can you have a moon environment and not cut the gravity at least a tad? Ugh. I can't say the demo wasn't representative of the final product, I just thought there'd be more to it.