I'm all for consistency but I use screen-lock on the iPad about a BILLION times a day... it really is a different device and consistency just for the sake of consistency would be a bad move.
I've never used mute and I think a major reason is I don't have a 3G iPad that travels around with me all day. I don't need to mute it like I would a phone. Maybe if I did have a "mobile iPad", I'd feel differently.
Screen orientation on the iPad is almost TOO sensitive. That's partially why I have to lock it all the time. The slightest change will send the screen spinning. I think I might prefer more of a delay or I guess just a more extreme angle to trigger the change.
Funnily the volume down->mute is the other thing on the iPad that I find too sensitive. The few times I've needed to adjust the volume down it almost immediately goes straight to mute. I've accepted this is okay though due to the lack of dedicated mute button.
Anyway, I'd much rather keep the screen lock as a slider.
+1
these are more good details -- please consider sending them to Apple via their feedback webpage:
http://www.apple.com/feedback/ipad.html
Thanks -
Macwheels