M.B.
I used it very successfully for many years... however, it doesn't work if you don't put it in! I think hubby mentioned that he could feel it, but it wasn't a problem for him... it was either me using a diaphragm, or him using condoms, so I think he felt it was worth it. (Besides, with condoms, we ended up with 3 kids.....2 of them unplanned, and 1 planned. With the diaphragm, we only ended up with 1 more child, and that one was planned.)
I didn't have any problems with UTI's... however, I still make it a habit to urinate right after sex.... (I don't use the diaphragm anymore... I had my tubes tied many years ago.)