I'm only about 2 hours into it but here's my impressions so far.
Lots of neat gameplay elements. Driving is heaps fun. shooting is different to what i expected, more of an emphasis on covering and reloading and timing rather than just being an awesome shot. Lots of 'minigames' (for lack of a better word, it all flows quite well) using the wii controls quite nicely, for things like rescuing people and dealing with obstacles. Sometimes it can get annoying with the game treating you like a baby telling you EXACTLY how to do all the different motions, but hopefully this goes away as I get further into the game.
cool atmosphere. It's cheesy and makes no excuses for it, but also has a kind of Resident Evil vibe where it's serious as well. I don't want to compare it to anything because it feels quite unique.
Heaps of unlockables and upgrades and stats and awards. gets a bit confusing. Cool feature you can replay levels straight away after finishing them, and even go back and find items you missed or rescue people you missed or killed.
Lots of variety, but I wont spoil anything. Graphics aren't the greatest, a bit blurry but they are consistant and lend themselves to some spectacular moments.
Music is ok, it's basically the same MGS sounding tune over and over. Hasn't stood out to me yet.
Main character is a very likable dude despite saying **** every second sentence.