The biggest problem with this game is that the average budget and length of current FPS's really don't allow for this kind of game to really work. If this kind of game is work, first they have to make the gameplay equal in length, second it must be fun for all three species, and finally that have a well written story that seamlessly connects them together.
10 hours is not a number that really breaks down into three evenly, so at least somebody had to get the short stick. What is worse is that they thought they must give off two short sticks and gave them to the title characters. It also means that each campaign is as brief as Halo ODST.
The Marines having the longest campaign and having the worst is a real problem. It is just in the dark run in gun gameplay like from Doom 3. However, at least Doom 3 had many creatures to fight, the human part only has one, the Aliens (the dark crawler of vents alien). This not only sounds frustrating and repetative, the fact that Aliens rarely pop out for most of it makes it really boring. The developers promised interesting and new alien species which turned out to be a big fat lie. The Alien campaign, while having more juicy humans, has some major problems trying to move in for the kill with Mario Galaxy like movement with Mirror's Edge persective. The Predator's can be fun, but has a very wonky close combat system. Being that the Predator is all about close combat, this can really frustrate.
The story less seamlessly ties together the plot thread together then a glues them to each other at random points, leaving many holes. Rarely do the events of any one story actually feel they impact the events of the other two. As Yahzee said, the Predator's rarely appear in any missions but there own. The whole "its a Predator temple" feels like a shoe in for the Predator's into the story. Given the fact there are many, many, many more references to the Alien series then the Predator series, one can easily see where the developers fanboyism lie.
