I made it on my own brand new Atrix HD LTE and I'm very pleased with it.
it's easy and very effective.
I paid 54$ for the EB40 battery (an OEM Razr MAXX battery) and only had minimal mods on the phone internal frame to make it fit.
you will find some details in those posts ( I don't want to repost pictures from other members)
feel free to add your own pictures and comments
from a strictly technical standpoint, it almost doubled the time between charges, going from a 1780mAh battery to the MAXX 3300 mAh EB40