They really are amazing, and it's a pretty plant too. But Anne, be a little bit careful, as some people are allergic to whatever that weird chemical in them is. (a protein called Miraculin, if google is to be believed) If you let other people try them, make them taste just a tiny bit first. Mouth tingling, itchy rash, cold sweats and nausea have been experienced but are thankfully fairly rare. But I know at least one person who is allergic to them.
If you try tasting grapefruit with miracle fruit, it almost tastes overly sweet to me. Like you poured on a whole bunch of artificial sweetener. Lemon juice is fantastic, though.