Mooncups are GREAT 
Seriously. They do take a couple of periods' worth of use to get into, but then, iirc, so did Tampons, but it was just so many years ago you don't remember the ickiness of picking the wrong size accidentally, leaving it in too long etc.
Mooncups are good for you, not just the environment - both my friend and sister whom I've converted swear they get fewer pains with their periods.
My period is also shorter with the mooncup - really - I think it's because Tampons keep 'leaching' moisture out of you after the blood/ tissue is soaked up, so your body 'compensates' by producing more fluid. Whatever, my period used to be 4-5 days and is now 3. Also, it doesn't matter if you leave it in for a while, and if you are regular, because it doesn't 'leach' like a Tampon, you can put it in early and then - voila - no stains/ mess!
Would never, ever go back - PLUS I never have to buy anything from Tampax/ Always again, ever!! £17.99 is it, all I spend on periods for ever...