Drums:
Rubber feet on the bottoms of the drum set so it wouldn't slide away.
Tension-adjustable pedal
Angle-adjustable drums

Guitar:
(Preference) positive tactile feedback on the strum. Doesn't have to be hugely clicky like GH, but at least have some kind of stop.
Maybe a wah-wah pedal too to make the most of the effects selector.

Mic:
Integrated controls, at least up down, back and forward.

Gameplay:
Drums and Mic should be able to go into overdrive on command. Being tethered to the score is no good.

Content:
It's going to be absolutely critical for Harmonix to keep releasing new downloadable songs online. They need the hits too, 3 song metallica pack and what the hell? Where is Unforgiven, Nothing Else Matters, or Master of Puppets?

They're doing 3 songs a week right now, I would say that's the bare minimum. They will need to ramp up the DLC to keep the replayability high on this game. Its only been a month and all my friends and I have played GH3 to death. We love RB more, but $170 is expensive for 60 songs. I think people tend to digest the cost easier when they know they can go online and pick up 10 or 20 more of their favorite songs too.

Russians piloting Battlecruisers? Only if we can get the rednecks to drive the siege tanks.

Oh yeah and we better get started on researching the Yamato Gun at the Physics Lab now.

The MJOLNIR's had too much robotic enhancement, they broke the user's limbs before the Spartan project came along. Sign me up for the Spartan project, as John 117. =D

Oh, and I unlocked it for free. So I'm paying $65 for the same plan AT&T charges $100+ for. =D win win win situation.

I left a Blackberry Pearl for the iPhone. I'd give the Pearl's texting a 10. I give the iPhone's an 8.5. Treo's and Q's are 9's. Any T9 phone is a 2.

Every other phone does pictures, songs, maps, youtube, and browser a 5/10 and the iPhone does it a 10.

Granted I could absolutely flyyyyy on text's and emails on that BB. But I was willing to give it up for the total media device.

I left a Nokia N80 for my Pearl, and I left a Sony Ericsson P910i for the N80. So far, the iPhone is the best overall phone I've had.

I'm posting from a jailbreaked but still locked iPhone, come on I deserve this.

Kodak and Dual Lens ftmfw.

6 hour countdown to iPods... Apple store down yet?

I wanna see "Segway chases down cop on gunman."

Whatever it is, it'll require memory sticks to boot up, it'll only read mini discs, encode only in ATRAC, and only be compatible with Blu Ray Discs...

Ensuring that it'll never have market share because of proprietary media.