Love it....I use Reason 3 on one PC and then 4 on another...I've been into it since about 04. For some reason (no pun intended), it's easier for me to sequence drums the way I want them on Reason 3 and then finish the rest of the beat on Reason 4. Just don't install both on the same PC...I did that once and they conflicted LOL.
I can "almost" do ANYTHING music related to a beat with it. Sounds are endless as compared to hardware (which is what I like most). And it's EASY to go back in and re-edit your work to make it 10x better or just spice it up later...as long as you have the original file and the sounds.
I doubt I'll be switching up anytime soon.
Fiev.