Yes, I've done it a couple of times now and there's some really good videos out there which will help you - watch them a few times before you start and watch them again while doing the upgrade, step by step. If you have a decent toolkit like the iFixit one, you just need some patience and a nice big, clean working area.
Like
@TwoH says, the heatsink mechanism they use can be a bit daunting due to the force you need to maintain on the brackets to screw them down, but I wouldn't let that put you off.
Personally, I found getting the board out to be a bit fiddly - I think its the SD card slot which makes it a bit of a pain. The only thing that I will always be nervous about are the edges to the screen which seem precariously thin, so just need to be careful when taking it on/off.