is mobileme worth it? best iphone trackign device (if lost)?

Hi guys, i have several questions regarding tracking my iphone 4 device on verizon.
How does mobileme work and do you guys think it's worth it?
If my iphone was lost, how will i be able to track it using mobileme.
If it runs out of power, is it still able to track it?
Does using airplane mode disable all types of GPS tracking including mobileme?
If a theft stole my iphone then restored it, will i still be able to track my iphone?

And it'll be great if you guys can post your experiences with using mobileme =)

1) Worth it for me with other features of MobileMe including "Find my iPhone"

2) From the me website or another iOS device using your MobileMe login and "Find my iPhone" app.

3) No tracking without power.

4) No tracking in airplane mode.

5) No tracking after restore.

If you phone is stolen you need to login in as soon as possible to set a passcode lock or wipe your device remotely. The passcode lock may buy you some time, but the phone can still be wiped out.

If you're only interested in the "Find my iPhone" feature, you may be able to use it for free. As noted here, it's "free on every iPhone 4 with iOS 4.2 or later" assuming you qualify (you have to be in a supported country for instance).