My favorite is Jetpack. I feel slow and immobile without it. I use it all the time unless the map is a whole lot of close quarters.
I don't see the big deal with Hologram, I dislike it.
Active camouflage is pretty good too. First, the messed up radar gets people paranoid and on edge; which is how I like my victims to be. I'll try to assassinate them, although I may just throw a sticky, or get further behind them and unleash a hail of bullets.
Beat Halo 3 campaign in a few hours and I got bored of the multiplayer quickly. It'd be nice if we could actually create classes like in CoD. I get bored of the same old weapons quickly. :/
I'm going to the Fan Expo Canada, just for the gaming expo. I hope I'll get a chance to play a demo of Halo CE: Anniversary Edition, and get a code for an energy sword for my avatar. I really can't wait to explore the first Halo again!
Btw I like the idea of switching to classic mode.
I believe it will be like Monkey Island, you'll just press a button for it to change; probably SELECT.