The cartoon graphics thing (BTW, you might want to tell him that's "cel-shaded"), sounds like something he just mentioned because he wanted to piss and moan about the game.
Modern Warfare 2... variety...
What, between rapid-fire, burst-fire or single-fire with stopping power or without?
And on the final point, those classes serve their purpose to the team.
The engineer guards areas, the sniper takes out VIPs (medics and engineers) and the spy stops engineers, snipers and medics from getting too cocky, because he rips their spines out.
All of the classes are designed to counter one another in certain ways.
I've got the slight feeling your friend is a lone-wolf CoD player who can't get that a game called Team Fortress 2 might have a heavy emphasis on working together, that might be his problem.
CoD might be making a whole generation of individuals who never understand teamwork...