I use Linux mint and Windows 7.I used qwerty for 6 years, but I didn't type the correct way. So, I taught myself to type correctly a month ago, I reached up to 40 wpm, then I wanted to switch to another layout, I don't know why. :p
So, I found Dvorak, its good, but very different from qwerty, so, again I was dissatisfied. I was googling and googling and ----Eureka! I found Colemak. It is a great Layout but I have some problem with "O" "E" "I" "s", I guess I am new that is why, have only typed for a week, a total of 30 odd hours. Currently I am typing at around 20-30 wpm and its improving daily.
Practice is the key to learn any new keyboard layout. If you are switching from qwerty it will be a easier layout to switch to. Dvorak made me crazy! :p