Going to my first rave. Experienced MSDS/ecstacy users: Are the advertised side effects true? What negative effects should I expect?

My boyfriend and I drink very socially and regularly, we've also smoked pot quite a bit in the past, but this is the extent of our drug use. We are going to our very first rave over the weekend and would like to try MDMA/ecstacy.... A few questions... I heard lack of concentration and motivation is a side effect for up to 1-2 weeks afterwards, true? My bf has a very demanding job, would this be an issue? Also, worried about the "lows" experienced a few days following. How safe is it to buy pills at the rave?