Well of 20 people (friends and a few randoms I have played with), all but 1 didn't love the game. And basic common sense as well, like you said, people enjoying the game don't generally make a thread topic of "who else is gonna have a great time playing destiny tonight?!!?!?!" They're just in a hurry to get to the tower and pick up their bounties and do whatever else they want to do in the game that day. As for forums, it is quite clear that most people on the forums have bad things to say about the game, but it is obvious they are just the minority, who ironically, also tend to have the loudest voice on the forums, as with most gaming communities, sadly. But mostly, my educated guess at percentages comes from the stats of how many people are playing, and for how long they are playing, and all of that. The post beneath mine sums it up quite well.

Bungie claimed 3.2 million daily players or something close to that. Even if that number is ridiculously wrong, there's only several thousand comments on each post. That's roughly 0.003% of the daily player base if you give a lot of wiggle room. Food for thought lol

That's bad math dude, your assuming everyone who has a problem with this game is commenting on the forum! I play with at least 6 people who couldn't give a monkeys about the forum but have a problem with the game