From the research into it I've done yeh there are side effects, but when you compare these with the side effects of the female pill they are miniscule. Also I'm damn forgetful, and I still manage to take the pill, mainly because I don't want a baby! I'm positive that if a guy agreed to take the pill then the fact he's a bit forgetful will not stop him taking it effectively, because lets face it his life will be messed up just as much by a baby as the mothers would (potentially, obviously not if he just legs it...but then why would you be with someone like that anyway) Final point I know a irl who reeeally wanted kids, and 'forgot' to take her pill her bf didn't ant kids and now she's pregnant, so I definitely think that guy would have wanted the option of a male pill.
Me n my bf have spoken about it and he has said that as soon as it is available in the UK he will be on it, he hates the fact that I have to carry the entire burden of our contraception when he gtes half then fun from it.