Great game if you love the first 2, then you'll love this too. Its just as atmospheric as the first 2 when played solo
Its worth noting I played the entire campaign solo and it felt just as atmospheric as the previous 2. I can only assume some of the complaints on the atmosphere must stem from playing the campaign in co-op mode...but lets face it its hard to keep that atmosphere if your gonna play in co-op. That said, now i've completed it solo im itching to play it through in co-op mode too.
I played this game on Hard and it felt right for me. I think I played the previous ones on hard too, so the difficulty must be about the same as the previous games (when played in solo mode).
The gun system was a bit odd a first and I wasn't sure that I liked it. After getting to grips with it though I really enjoyed the flexibility of crafting your own guns. Being able to combine any 2 guns into 1 (primary and secondary fire) allowed for more tactical combinations (like a 'shotgun/rocket launcher' or a 'plasma cutter/flame thrower' for instance). In the previous games you had to switch between these weapons which made the gun play slower
All in all this is a great game and definitely worth playing, the only one bad thing I can say against it is the the inflated price EA wants to charge for it