I've heard a lot of people have completed the main story line in a single day... I was expecting people to get at least 20+ hours out of it, pretty much everyone has aired some level of disappointment, so I'm glad I never jumped on the hype train.
Though I've always hated Halo for having the most dull gameplay of any game ever, short of Mario or Sonic, so I guess I'm not surprised that Destiny looks like a prettier carbon copy of it.
I'll stick to waiting for MGS5.