well for my phone, the incredible, it was a big deal. lets see, some updated things were
mobile hot spot is amazing to use. being able to give internet access to any lab top from my phone for free is awesome. i really dont need to be paying for internet anymore since my phone does it for the computer now. and its still quick!
the battery life became 20-30% more which i already actually noticed a difference in which is great and important.
the speed itsself on the phone on load up screens and internet access is much quicker.
flashlight app is for the first time working.
all my icons changed to a nicer font and style. like 3g, bluetooth, gps, volume, navi, album art, calling screen, and more.
the text layout changed to be wider buttons which was awesome.
amazon mp3.
turn your phone any side to view the screen, not just to the left anymore.
new widgets.
being able to move all apps or anything you want to your sd card.
auto update on all apps you have instead of manually clicking each one.
and a few others, but thats what i remember off the top of my head.
to me, the new look of widgets, 3g mobile hot spot, better battery life and faster speed was the big ones what was worth it.