Wow, the hardcore argument is total bullshit.
I won't dismiss anyone who plays it - but let's not act like it is something it's clearly not.
It is not an entirely different game by any means. I would compare it to something like regular slayer/no-motion sensor slayer in Halo. Granted, it makes people play more carefully less they get jumped and killed - but it's still the same game, and has a high possibility of attracting campers.
This is an issue ten-fold in Black Ops due to a combination of killstreaks, kill-cams (or lackthereof allowing for campers), even faster time to kill weapons (making spraying that much more effective) and team-killers.
I spent quite a bit of time in MW2 Hardcore and have given it 15-20 matches in Black Ops. It's the same bullshit netcode, with the same bullshit near-insta-kill weapons, with the same bullshit campers and the same bullshit killstreaks. The idea is sound - and there are plenty of people who play Hardcore like it should be played (that is, moving swiftly, attention to detail and being careful/observant when moving from cover to cover), but ultimately, a significant portion of the people who play HC are merely amplifying the issues with COD Multiplayer.
To clarify, I never had an issue busting a 1.8-2.0 k/d in Hardcore modes. The increased usefulness of spy-plane, sentries & SR71 made some elements of the game wonderful. Even better - the assault rifles become the mid-range powerhouses they are meant to be, snipers become long-range rape cannons and SMG/Pistol/High-ROF AR's become short range winners. But it doesn't prevent any other bullshit, still has the overarching 'AR owns all' classes, and encourages corner/stairs/bush campers.