Metal gear online is a great game, one of my favorite online games of all time, but it has it's fair share of issues.
The control scheme is by far the best in the Metal Gear series. You move like most games with the left analogue stick and move the camera with the right. Aiming is done with L1 and firing or attacking is done with R1. While aiming you can also press triangle for a more precise aiming mode. The use of the stun knife in cqc(close quarters combat) is also done with the L1 and R1 buttons.
The level designs are pretty good to say the least. Graphically this game is beautiful and does offer 1080p display. Most of the levels are in areas lifted directly from the metal gear story. Some are setup for mostly close range combat, while other levels promote the use of snipers and other long range weapons. These long range levels usually have paths around the sniping area for players who prefer a more direct approach.
All of the regular match types are included such as DM, TDM, Capture, as well as some new game types such as Team Sneaking.
One major downfall of the game is that it is in the third person view. This is not normally favored in shooters because of the ability to stay in place and look around corners without ever having to show yourself(camping) It becomes very frustrating when opponents continue to do this in team deathmatch. The only remedy to this is throwing grenades hoping that you hit them or by simply going around. The game does show you the player that kills you when you die, but this is a feature the host may choose to turn off.
The biggest problem with the game is the way too common lag time. If you think it's always the other players, think again. I'm not sure why, but the entire MGO system has a slight lag time to it. Some players lag more than others, but MGO itself lags most of the time. You'll often find yourself shooting until your clip runs out to have your opponent kill you before they die from the shots you fired a second and a half ago.
Some expansion packs have been released since the release of the game. The expansions include new levels and special characters that can be turned on by a game host. Both expansions together right now cost about 20 US dollars. They may or may not be worth it to you as they are new scenery, but many players don't own the expansions and therefore cannot play in the new levels.
Overall MGO is a great online third person shooter that is definitely worth checking out if you own a PS3. If you can get over the online lag, this is very solid game. Also if you own a copy of Metal Gear Solid 4, Metal Gear Online is included on that game disc.