I don't know about Halo. Played part of the first game, watched the Rooster Teeth series Red vs. Blue, and that was about it. I'm also not a huge fan of Mega Bloks. So why would I buy this set?
2 reasons. 1) buildable turret and 2) ATV that is also a miniversion of the Warthog. Also, it was on sale. Mostly that last part, since I've been passing this in the toy aisle for a year without picking it up. I'm sorry, but I was burned on the Mega Bloks Warthog when they left out important blocks and I had to stop about halfway into the build. Ever since then, I haven't been too eager to get Halo Megabloks.
But this is a nice set. The Mongoose is pleasantly solid and looks a lot nicer than I thought it would while I was building it. It looks like a real toy vehicle. The Turret is kinda weird, because it's an alien turret and thus the gun looks... well it looks really fake. Really, really fake. The alien minifigure is kind of nice though, and I like his alien energy sword. But that doesn't redeem the fakieness of the turret. Still, at least the turret spins. Like a turret should.