Thanks to HTC I was able to root my EVO3D. I have not put another ROM on it and I am not going to yet. I am very happy with the stock ROM and everything works great but it is very nice to have the phone rooted so that I can do some things with it that were not possible before. So if you have an HTC phone go see if they have unlocked the bootloader for your phone and just follow the instructions. Here is a link.
Good luck and remember that this will void your warranty. Just because HTC does not mind you doing this that does not mean that your carrier will want you to do it.