Not to be an advertisement but...
It works. If you don't grow on it then you should take a look at how you're eating/training because something is seriously wrong.
That being said, the gains aren't as solid as I'd hoped (Read: A lot of the gains were water), which is a major psychological dissapointment by about a week after your cycle is over. Also, I would not go any longer than 2 weeks at a time without having clomid on hand, as I noticed definite suppression when I did a longer cycle.
As far as side effects, if you stick with a two-week cycle there really aren't any. It claims not to convert to estrogen, and I believe that to be accurate.
I like Mag-10, but it wasn't worth the cost for me.