Great concept, depressingly weak execution.
The combat is all right. In addition to the obvious ways to kill Nazi mooks (guns and grenades), you can also get up close and grapple, wherein you can turn the poor fool into a human shield or just kill him (sometimes fairly creatively, like shoving a guy burning documents into his incinerator). Turns out building skyscrapers (your character started as a construction worker) makes you pretty strong.
The story has unrealized potential that has been explored in numerous "What if?" books, but Codemasters failed miserably in single-player: it's a straightforward, linear campaign with only seven levels and objectives that amount to go here, shoot this guy, blow up that tank. Bog-standard FPS fare that you can complete in three or four hours. One of its selling points was the use of weapons extrapolated from captured Nazi blueprints, but here again the potential is unrealized: the most interesting weapons (e.g. a sniper rifle with an infrared scope, or a predecessor to the assault rifles that are standard in today's armies) appear maybe twice each; mostly you'll be using a semiauto rifle and a submachine gun.
Nice try. Note to the devs: next time you have a great story concept, you might want to ACTUALLY MAKE USE OF IT.