First half was suspenseful, second half...not so good

WARNING - SPOILERS BELOW

Would be good to hear other people's thoughts on this, so here goes:

I felt this movie started off great. The depiction of an ice age era and how the remaining humans have banded together to forge a functioning stronghold was realistic. The distress signal and travel to colony 5 painted a grim view of the world. At colony 5, the atmosphere of impending doom, the cinematography, the ambient noises were excellent and having not watched any trailers or read anything about the movie, I was really captivated by what was happening. It was clear something scary and vicious was inside the facility. I had no idea what it was, I was scared and I was intrigued. This all went on for nearly 50 minutes, which was great as the director built the suspense up very well. At the time I felt this movie was on a 8 or 9/10 for me.

The second half of the movie was unfortunately very average. I felt that all the logic and realism that the first half was built on was partially thrown out the window, here are two of my main points of criticism:

1) The human cannibals - many posts on here, and even Laurence Fishburne's character in the movie suggested that they were survivors that went crazy because of hunger. A unique take on the saturated zombie market, which is a nice touch. But
I think the director then fell into the trap of 'we need to make these cannibals less human and more like zombies that grunt, scream and can't communicate'...well, thats just bullocks! Just keep it simple and realistic, so what are the cannibals?

Either they are hungry crazed human cannibals, in which case they will be smart, calculating, act like normal humans, have the intelligence of normal humans, have normal human strength or perhaps even less so if they are malnourished, can infiltrate the human colonies to deceive etc... OR they are mutated/zombie/humanoid like creature that are strong, fast, shriek, scream and devour humans. The director tried to do a bit of both, and I don't think it worked that well.

2) Mason - why do so many movies have to make a dumb characters that won't exist in real life? So a guy escapes as the only survivor from colony 5, comes back to say there are cannibals and they are coming. So a composed ex-soldier's typical response to that is 1) lets not ask anymore questions about what happened at colony 5, and 2) lets just not believe anything the survivor says, but hey, lets also tie him up and lock him up. I mean, common...Think about what made Aliens a great movie? The characters were all believable and behaved in how we would have behaved. Imagine if the last 40min of the movie involved the entire colony 7 banding together to devise a strategy to defend their home, and they fortify their stronghold in the dead of night, in the wake of a march of crazed killers/mutants. The suspense and climax would have been excellent. Instead, we get an uncompromising commander who doesn't believe anything, a cliche scene of a guard who was meant to be watching the security cameras and only leaves just when the invaders arrive to surprise them. Oh, and did I mention more cliche - the unbelieving Mason meets a timely death, and just as his bomb went off the leader of the cannibals just manages to jump into a vent, and yes more cliche, he is locked into a 1v1 contest with the main protagonist in a punch out session. After the 1v1 contest resolves, the protagonist emerges victorious and leaves just in time to catch up with the remaining survivors. During the last cliched 30min or so, I didn't panic for colony 7, I just thought stupidity of character decisions and cliche scripts deserved no respect.

Rant over...

I felt this movie could have been such a great one if it wasn't for some poor decisions on the script in the second half of the film (which I felt was a poor 4/10 - so overall I think IMDB's rating of The Colony does reflect what the film deserves, which is a very average movie).