Does about as much wrong as it does right, but still seems like something you will want to experience.
First lets get the bad out of the way. One of the first things you will notice is that the game tends to start playing before your graphics have fully loaded. This kind of thing was rampant in Halo 2 and and to a lesser extent Halo 3, but still something that will annoy you, but does not affect your game play.
Autosave is not very reliable, at some points it will be saving every 5 minutes, this is usually when you are on the citadel, if you are in situations with combat the autosave does not kick in, so remember to save. There have been numerous times when I have lost a lot of ground because I forgot to save, but this can also be attributed to user error, so you can live with it.
The few boss battles I have done have left little room for strategy or freedom to find alternate ways to finish them. Mainly they have been kill boss as fast as possible or get swarmed by adds. This type of boss fight only works in MMO's IMO. This feature will have you replaying most boss fights and having to relive most conversations and cut scenes. Small tip to help here most conversations can be skipped by hitting X.
The last and probably the biggest buzz kill for me is the completely retarded AI you have to deal with. They will stand in front of you so you can't shoot, if they have people running up and beating on them they will just stand there and take it, even if you try to tell them to rally to you, or give them a place to go, or tell them to take cover. They have cost me boss fights, had one issue where I had some knocked on the ground from a biotic power, I move in for the kill, and my team swarms me, gets in the way of the target, and just stand there and didn't do anything. This has been the biggest draw back to the game, and is IMO the ultimate factor in keeping it out of the higher scores.
Now for the good. First off you will notice the graphics are just amazing (after they have finished loading). Most games will be hard to pressed to beat them, as you can see a good arrange of emotions on the faces of people you encounter.
The character customization allows you to create a very distinct face, the only thing that would be missing is altering other facets of the character. When I am making a character I like to mess with physique, muscle tone, height and weight to truly make a character my own. But this system is passable.
Wide selection of weapons and armor in the game to choose from, however most items you will find as store prices are a little over the top, but luckily the game offers plenty a crate, weapons caches, safes, and other items that you can loot to obtain new equipment.
You will be hard pressed to find better voice acting in games. With big name celebrities like Seth Green adding their voices to the game truly makes you care for the characters. You are given six classes to choose from and later in the game receive specialized classes. The story is very engaging, and makes you care about what is happening in the galaxy and what is happening in your characters life, whichever walk of life you choose for them. This final feat with the story is what makes this game something special and when you are past the annoying and frustrating parts of the game you can truly enjoy. My only recommendation is don't play this game when you are stressed otherwise the flaws will overshadow everything good this game does