I've done Mkat, I wouldn't say it was bad, worst sideaffect I've ever had is massive memory blanks, but I was drinking as well so its hardly supprising, on my 20th i managed like 16 pints and hold it down because of the stuff. Gave me a nose bleed for no reason 2 days later once, so not doing that shit again.
Just had a great night in with a girl, nothing happened just shes well nice, gotta avoid the friends zone though.