Advances in contraception is typically great news (unless you are of the school of 'thought' that prefers an oversized litter of offspring). This BBC article also discusses the new responsibility that comes for men with a male contraceptive option, which brings me to imagine the added positive effect it would have on the dynamic of the actual relationship. Based on my limited relationship past, I'm confident that having the option for both to share the contraceptive measures would relieve one generally touchy issue in relationships - avoiding pregnancy.
I personally hate birth control - it feels very unnatural, causes weight gain, and although it 'regulates' your monthly periods, it is impossible to know the long term effects the pill could have on your reproductive organs in the future (yes, every body reacts differently, this is just my experience I am drawing from here). Men reproduce sperm all the time - they do not have 1 stash of eggs set aside for their lifetimes - logically, this leads me to believe that long term effects from a male contraceptive might be less severe. For these reasons, when I have chosen to go on birth control in the past, it has come with a touch of resentment - only my body is being put on the line here, and that added responsibility to take the pill every day at the same time is ultimately all mine. We can only have sex without a condom if I go on birth control; if I forget to take the regular pill, only I can take the morning-after pill; if we do accidentally become pregnant, it is because I forgot to take a pill...feeling physical and emotional burdens is inevitable, and at times might even manifest as tension in the relationship or during sex.
A male birth control option alleviates many of these issues. Obviously two forms of contraception are better than one, and I personally would be so much more willing to get into daily pill intake knowing my partner is getting into a monthly injection as well. So yes! please! let's approve this fast! When both people in the relationship have a constant reminder that they are both part of conception, that's one step closer to a gender balance!
And to those men who might feel emasculated by the thought of shooting blanks....really??
