I've had my diva cup for about two months, and I will never, never, never go back to using anything else. OMG does this make having your period almost nice! I feel SO much cleaner than I ever did using tampons (never mind pads, those, IMHO, SUCK). There is no noticable smell using the cup, which I love (working with men, I'm always worried that they will smell the odor produced when using a tampon). I even use my diva when I'm not on my period sometimes, just to collect the discharge I produce on a daily basis (yes, my vagina hates me, apparently). It's perfectly comfortable, and I forget about it often, and wake up in the wee hours of the morning and freak out because I haven't emptied it since I put it in the previous day...oops.
The only downside I can think of is that it's larger than a tampon, so it's less discrete to slip in your purse when you're not sure you'll need it (unfortunatly, I forgot to insert when I thought I was going to start my period, and had to have my boyfriend bring me a tampon at work because they are so much smaller). Mine is also tinged a brownish color already, which bothers me a little bit, but is to be expected, I suppose. I'm seriously considering buying a diva for my little sister for Christmas, because I love, love, love mine so much!