Gods, no, it's not fun.
Ok, there are some transwomen who don't mind it so much, but for me, that wang is worse than useless. The idea of actually fucking someone with it makes me nauseous. My last boyfriend liked going down on me... sometimes, if I lay still and concentrated really hard on some elaborate fantasy, and tried to ignore physical sensations as much as possible... he could get somewhere with that. Usually it just wasn't worth the bother to me.
For me, "sex" basically means "we make out for a while, then I go down on them". I look forward to surgery as something that will let me finally try out this fucking thing everyone talks so much about.