OK so maybe Swype isn't the best keyboard for everyone, but it is for me and has been ever since I got hold of it on my, now ancient, HTC Desire. I've tried every other mobile phone keyboard out there but nothing seemed to ever come close to the speed and usability of Swype. I got so used to it that I could nearly write whole messages without looking at the screen, it was very useful when driving (honestly though, don't text and drive, you will die).
I've been using the iPhone for 6 months now and I just forgot how bloody good it is. It makes my iPhone texting look snail-like-slow. I can bang out messages super quickly on Swype, some words can actually be typed out quicker on Swype than they can on a fully fledged qwerty keyboard, especially long words.
If you have an Android phone I highly recommend trying out Swype. It does take time getting used to but once you do you'll wonder why you never discovered it before. Also it's completely free so you're not losing out on anything.
If you don't use Swype and prefer something else, leave it in the comments below.