Most of the conversation is about graphics, and so the one dude that thinks its similar probably influenced all the other people.
Its similar on paper, but in my opinion it actually takes some of the things Reach did and does them in more interesting ways. It basically stole some of the armour abilities, but you can use them all simultaneusly on the fly. So for example you can sprint, jump over a building, then go into sort of overshield, kill someone and then go camo to sneak away.
Its quite cool, and quite fun - the base movement feels really jerky, and so mostly instead of people sort of doing all these cool manouvres - you end up running at eachother shooting your assualt rifles at eachother. So in a way it sort of plays like Halo, but a way people should never play Halo.
The base movement is quite nice though, allowing sort of super jumps, and a decent speed of movement, its just hampered by what seems like lag?
The core gunplay is much more like CoD, with ADS and so on, but when you go head to head you both end up putting on overshield, so it generally comes down to spraying at eachother for a while and hoping your more accurate. So its like CoD's gunbattles but prolonged much longer. I think if the game had a BR equivilent (and strafing was possible) it would be awesome. Again, the core gunplay feels NOTHING like Reach.
It also stole the idea of Hologram, you can get a gun attachment that shoots holograms out of your gun lol but apart from on paper the shields and armour abilties are present, the gameplay plays NOTHING like Reach, and the armour abilities are a lot more transparent, and dont influence the gameplay as much.