Pros: Brand new adventure, graphics, mix of stealth and action, realistic details.
Cons: A few minor gameplay issues, not the movie actors' voices.
The bottom line: Whether you are a Bond fan or just love FPS/stealth games, you've got to check this out.
I should start right off by saying that this is not exactly a review of the XBox version of the the game. I am actually playing the PC port of the game, but Epinions doesn't appear to have it listed under PC, so I thought I'd do it here since I'd imagine that XBox and PC versions are the most similar. The biggest difference is probably being able to use a mouse to look around smoothly on the PC.

Nightfire is a great game for Bond fans young and old. It's a good mix of stealthy spying and first person shooter action just like the movies. A lot of games have been made lately that clearly took inspiration from the 007 movies (Deus Ex, The Operative 1 and 2 and Hitman to name a few.) The folks at Gearbox Interactive used the Half-Life engine to create a game that's so much like a Bond movie that there are times that you'd almost swear you were watching one. It even has an opening action scene followed by a music video opening that's just like one of the recent movies.

The characters are hightly detailed and well modeled. If you can play it with anti-aliasing and a high resolution turned on, they look photo-realistic. If you get close to one, you can even see their eyeballs move as well as their cheeks and lips moving when they speak. Their motions are fluid and lifelike with few repeat actions.

The enemy AI is pretty smart. They duck for cover if they can when you shoot at them, they hide from you and attack when they have a good shot at you, in short, it's a bit like playing against people online. The difficulty settings adjust the AI pretty well. I had an easier time getting past guards and avoiding getting shot in the easy mode than the medium mode.

The background detail is pretty good. I was able to get a good balance between eye candy and smooth framerates with my 128 MB ATI Radeon 9700 and 512 MB of RAM by setting the resolution to 800 x 600, 2X anti-aliasing, setting the flare accuracy on low and all other settings on high. There is enought customizability that one should be able to get it to play on the base recommended system of 500MhZ Pentium III, 128 MB RAM, and at least a GeForce 256 or equivalent.

Being a console port, the gameplay is a little awkward, but not nearly as much so as the Spiderman or Batman game ports. Since it's mostly first person, there isn't the annoying problem of losing James behind a wall or not being able to see where you're going when you turn a corner. There are the issues of specific actions only being available at certain locations, and a slightly clunky inventory interface that I'v seen in ports before. These issues are minor and don't detract from an otherwise great game much.

The biggest negative of the game is the lack of voices from the movie series. The voice actors do decent impersonations of Bond, Q, M, etc. but there are times when it's obvious that they are not the movie actors. On the other hand, the faces of the characters are dead-on models of the actors. They must have used photos of the actors for the character skins because the detail is amazing. The in-game animation is very close to being as good as the cut-scenes (which is rare, even in recent games).

You get to play with some cool gadgets, some are familiar to 007 movie veterans while others seem to be new. The sunglasses that see in infra-red and x-ray are really cool. The weapons are modeled after real-life ones complete with realistic ammo capacities and reload times. This is no Unreal Tournament, you have to think a little before you shoot.
One clever game-play element is using the classic fanfare from the movies to let you know when you've accomplished an especially tricky task or when you do a death-defying jump or other action. That touch, along with the great title and background music really make it feel like you're playing Bond in a movie. The theme song is actually pretty good by itself. It has a techno beat to it like the newest movie "Die Another Day" which is great and really worth seeing in the theater.

A note about cheat codes for the PC version: they don't work very well. Once you get them to activate they work, but getting them activated is a challenge. Check out the comments for notes on the cheat codes.