I use clen regularly. If you cycle it correctly it works great. I am about 225-230lbs. I take 3 tabs spaced equally EOD. After I complete my 50 count bottle I may take a week off then re-up.
I do this during the winter when I don't need to be super lean.
During the summer when I want to be much leaner I try to take 4-5 tabs ED one week on, one week off. I cycle ephedrine on the week off. I don't think this should be done all year or too long. I do it for the summer only. I find comming off the ehpedrine is worse then clen.
Draw backs to Clen: 4-5 tablets make me a little jittery, even at 3 tabs I heat up really bad. I am always the guy who wants the window open or the air on. I also get a head ache during the start of a clen cycle. It goes away after a day or so.