Overated:

Half Life 2: Yes, I went there. Flame me if you want but let me say my piece.
I did thought it was a good game. There were a lot of cool moments in the game, such as when you were driving on the motorboat in first person. I also LOVE the sound effects and audio in the game, for some reason, the sounds that come on through picking up health items or ammo never gets tiring. The game also has an element of horror to it through the headcrabs and zombies. I still get nightmares from those poison headcrabs.

So why is it overated? Mainly due to the annoying PC elitists who badger me about how the PC version is better. (I own the PS3 version.) Well guess what? I only have a laptop and can't afford a computer powerful enough to play a pc version of the game. Also, I didn't think it was one of the best games I've ever played. (Most likely due to me bieng spoiled by other FPS's like Halo.)

Super Smash Bros. Brawl: I was kind of disappointed with this game. I didn't like some of the new characters, (Lucas? Really? He's basically Ness without a hat.) I didn't like how you can easily unlock all the characters in the game through going through the subspace emissary, and I didn't like how some characters were removed in favor of others. (Why Mewtwo? Why?) It's not a bad game by any means, but I don't like the direction it's going.

Underated:

Katamari Damacy series.: I'm surprised these games aren't more well known. You play as a tiny little guy known as "The Prince" rolling around a ball called a "katamari". The goal in each level is to roll over a bunch of stuff and make it as big as possible. In the later levels, your katamari can start out as big as a mouse, but can be as big as the moon if you roll over enough stuff. You'll soon find yourself from rolling up little toys to entire towns to entire continents!

It's a very strange game, and some people may be put off by it's quirkiness and japanese pop/techno soundtrack, but I think it's really good and is definitely worth playing.

Valkyria Chronicles: A game that takes place in an alternate earth around the time of the Second World War. Except it's called Europan War 2. You take the role of an university student turned tank commander, as you lead your squad against the Empire, who are attempting to take over your home country of Gallia. The game is a mix of an RPG, a turn based strategy, and a third person shooter. Think Fire Emblem, but instead of grid based movement, you move your units across a 3D field with a gauge that shows how far you can move, also during this time enemies who can see you can attack you.

With it's unique strategy based gameplay, it's great story, it's memorable characters, and it's cel-shaded graphics, this game is truly a diamond in the rough. Although due to people who actually played the game and spread the word about how good it was, it's sales boosted over the past year. The sequel of the game also came out recently, I haven't played it yet, but I hope it's as good as it's predecessor.