OMG.... MOH. I actually thought the SP was weak, however I LOVED the MP. I think for me it was the sound. Going from SP to MP there was a huge difference. You felt like you were holding the worlds biggest guns, yet your firing your pistol. There wasn't enough maps though. Least I remember going to the same 3 all the time. I've said this before about Crysis 2 MP, but MOH also has the feel of COD:MW1 (which is probably the MP game I've played the most).
You're very correct though. If you're paying $100 for a game, the SP and MP better not suck the giant ones. Anything I'm not too sure about now, im just going to hire out on my PS3 or Xbox.