No, not nearly, not since Halo3. I would say that the descent started on the 360, HaloCE and Halo2 on the XBox were a cut above, truly 2 of the best games ever for the original XBox. But then Halo3 came out for 360, and IMHO it lost it's mojo. I think the main problem was the co-op. The original XBox games had both players as master chief - you both had the same mission, you both looked out for each other. But with Halo3, one player has to be an irritating alien, so that connection is lost. I think that HaloCE was a little long winded, but besides that, the perfect co-op game. It felt epic... I mean some parts of HaloCE made my jaw drop, and it hasn't really dropped since then.
The xbox went from ''No idea how it can handle all that'', to ''No reason why it can't handle all that''. Halo3 is not impressive. HaloCE sold the Xbox to me, the first day I played HaloCE I went out and bought myself a controller so I could join in, then the following weekend I bought an Xbox. Sad for me to say but as good as the Xbox360 is, it has never stirred my loins like the original xbox did... it grabbed the PS2 from it's pedestal, and booted it right in the ovaries, and I love it for that.
Even with the addition of online mode - hell I used to get 3 friends together to play Halo, on team deathmatch, on one of only 2 maps that we played, and to me that was much more fun than anything I've done in a Halo game since. I played Halo deathmatch with people who haven't played a shooter since Quake2. HaloCE is a game that people wanted to play, wanted to be involved in all that action unfolding in front of them - people who hadn't held a controller before wanted to rip them from the hands of noobs and show them how easy it is to snipe. Really the only game that I can compare it with for split screen shooting fun, is Timesplitters.
I find that I just don't play co-op games online, I'd much rather play over LAN in the same room, even if that means I have to buy extra copies.