it all depends on the maps,
for SP I give the Russian and American maps 9/10; British maps haven't been given much thought though, so 7/10 overall.
The Normandy maps are pretty realistic, notice that the Germans attack you from one corner, when they fail they retreat and hit from another corner, unlike Spearhead and Breakthrough where the Germans just charge into your fire like Orcs until they overrun you or all die oOo:
The T-34 map makes it all worth it in my opinion, much better tank level than the Medal of Honor ones, the tanks move together, move fast and gun down infantry with their MGs hellfire:

MP depends largely on the server, lag, players (mainly if they're cheating or not), and if its modded or not, my experience has ranged from perfect 10 to horrible 0.