I haven't finished single-I had few bugs which made it impossible but I'm impressed.
And to multi, yeah, I like that but what I hate:
No dedicated servers so I can wait for players/game 5 mins and then see the window "lobby is closed" or "host finished his session".
Huge lags sometimes.
And artificial extension of lenght of this multiplayer by adding 10 options of prestige-when You go to the next opt. of prest. you adds to guns, all challenges are deleted. The only things that remains you are emblems and titles..... so you have to master your 25 guns from the begining (if you don't know- each prest. opt . has 70 levels and druring them possible is only mastering 2 guns[physically you aren't able to do more]).
However, I like this game pretty much and hope to see you on "servers". My steam is vorrtz.