Yo Guys! Had to join in the discussion here - HUGE Aliens/Predator fan - went to watch it last Friday and was disappointed.
I've read all of the comments above, but growing up watching Predator 1/2, I don't really feel this fits in particularly well. I completely respect the reboot, but the narrative structure and the combat has little to no innovation in regards to the previous films (falling off the cliff, Billy dual, fire 'Kill Me!' etc). The Predators themselves seem to have been toned down - a Yakuza member parrying blows off a Predator in that dual? These Predators are supposed to be HUGE (as in P1, VERY tall), yet they are portrayed in this film slightly sluggish and weak(er) - their masks being cracked off with bone, and dying with an abdominal slice? Also being fairly inept and intellectually inferior to humans? Hmm.
Enjoyed it as a film though, but in conjunction with appreciation to the series, I'm only just slightly putting it out of the bracket of aberration that is the AvP films.
One last thing - mud as a method to negate thermal was mentioned midway through - yet it took them (him!) until the end of the film to apply it!
Sorry for the rant, but I was expecting a little more!