Not as bad as everyone made it out to be.
I only played a little bit of single player but finished it on co-op and if you have the opportunity try and play it on co-op as it makes for a more flowing experience as you don't have to order Spock (or Kirk depends who you prefer) around the stage to scan certain object with the tricorder or to press a switch for you to advance.
As you complete objectives or scan object and enemies with the tricorder you will earn XP. This can be spent on unlocking new abilities for your phaser pistol, tricorder and stealth. One thing I disliked though was the fact that it would not save the second players XP so they would have to start from scratch each time. This probably will be different with online play. But I was only playing offline split screen.
The combat is similar to most 3rd person shooters. With your cover system. Aim to lean out and shoot etc. So if you familiar with games like Gears of War you should have no trouble learning the combat.
They have a stealth element added to the game which I found to be a good change from just shooting your way passed everything. This will require you to find hidden paths which will have you hanging from ledges and jumping between pillars similar but in no way as good as Assassins Creed.
There is also one ship battle. You don't actually control the ship which was a bummer but instead alternate between phasers and shields. You just have to learn when to activate the shields and when to start blasting away. There are some other elements to the game but I will let you discover them if your willing to play the game.
Graphics on the game were pretty average as most cut scenes are still trying to finish drawing the scene due to graphical lag. But this is common in most new Xbox 360 and PS3 games. The faces on some characters are done better then others letting you Identify the actor portraying them. Some you just know it's him cause you've watched the movies. Plus the environment isn't really all that spectacular.
Sound on the other hand is great with all the original movie sounds and voice acting being used so it helps immerse you in the game.
The controls handled just like you would expect from a 3rd person. With the only time it feels a bit chunky and unresponsive is during climbing scenes.
Overall the game is reasonably easy. With not much replay value. Unless you want to play it through as the other character. Trek fans will like it. 3rd person buffs will hate it and some will complain for the sake of complaining. But if your up for a trek through the universe I suggest you grab a friend and give this a go.