THIS is how expansion packs need to be done.
First things first, be warned that this game DOES have some slightly more advanced graphical updates over Episode One, but if you were able to run Episode One on max fine on your PC than this game should run fine at max, MAYBE a little lower.
That being said, 4 years after the original Source engine was made, the game STILL looks beautiful. There are some interesting new environments and some interesting takes on environments we are already used to seeing. The characters are far more animated and there seems to be quite a bit more variety in character models, which definately gives the game a more dynamic feel. The game looks nowhere near as beautiful as something like Crysis, but that wonderful attention to detail that Valve seems to be so good at isn't done wrong in any way within this little gem. At this point in gaming, some of the geometry may seem a little, blocky, after being so used to curvature in futuristic games, but then when you look outside, you realize that, considering how close to our time this game is said to take place, the geometry fits perfectly (excuse my long run-on). One last thing to note is that though the water looks beautiful on the surface, the underwater effects are quite dates and unrealistic (unless the suit is meant to fix distortions, in which case that would make sense).
As for the sound, you will hear no complaints from me. The new enemies sound distinct and fantastic, the voice acting is as good as ever, the music is better than that of Episode One and the game overall just sounds absolutely magnificent. It may even be possible to obtain a more complete aural bliss out of this game than you could out of Half-Life 2 itself. Yes, it is that good. The voice acting is worth noting again, because it is done so well for so many of the emotional scenes in this game, that it can be comparable to some of the best Hollywood acting. Those Vortigaunts can be especially amusing.
There has been a slight change to the HUD interface, which involves putting a little flashlight symbol near the ammo symbol. This is done because Valve actually seperated the flashlight's power from the suit's power (yes, that means you can run fast and use the flashlight at the same time, using independent power sources). This is a wonderful change that should have been done sooner, but better late than never.
The story picks up pretty much exactly where Episode One leaves off, at the train wreck. It follows through a series of emotional sequences that are better left unspoiled and ends in a climax exceeding that of any other Half-Life game. This game has everything that Half-Life 2 had that made it great, packed into half the gameplay time and multiplied by two times the quality. The action here is top-notch, with great gunplay, great escape sequences and even a fun (acceptably short) driving sequence. The puzzles in this game are well balanced as well. There are many unique sequences from navigating an antlion burrow to defending an are from Combine forces.
To add to the mix (thank you Valve) we actually have 4 new enemies, 3 of which are new Antlions. 1 of those antlions is utterly useless, the other is merely a physical and slight attack type change of the normal Guardian and the other is a different type of antlion altogether. The 4th new enemy is the Hunter of course, which is a very intimidating, resilient and powerful enemy.
Unfortunately, however, we don't fare as well with the weapons, with the same exact returning weapons (Valve still refuses to put in any sort of fun alien weapons like Half-Life 1 had into the HL2 games), though there is a new mini-weapon of sorts, that can only be used in the climax. And yes, it does seem like the pherapod will never make a return.
These are minor complaints, though. As for the value of the game, clocking in at about 10 hours and with a bunch of unlockable achievements, not to mention a complete (and interesting) developer's commentary, the game has its fair share of content considering it is merely a single-player expansion. That being said, I think it is fair to be lenient on the fact that it offers NOTHING new to the multiplayer, especially considering that this is an expansion to the Half-Life 2 SINGLE-PLAYER.
Overall, this is an experience that you will not want to miss. From the tense moment of your first meeting with a Hunter to the glorious battle between Dog and a Strider, this game will be nothing short of a satisfaction for those who decide to play it. Enjoy.
Graphics: 9/10
Sound: 10/10
Gameplay: 10/10
Value: 7/10
OVERALL: 9.0/10