Piglet

don't be scared by any stories on here, instead, read all the good things that are said on here, and all the cute pics! kittens are ALOT of fun! work too, but it is worth it! the only problem that you might have is if your resident cat will accept them, and 2 might be kind of a shock to an only cat. ask your vet, there are good ways to slowly introduce them, and be sure to give the resident cat LOTS of attention after you bring in the new ones. if her/his routine is not changed drastically, he or she should be ok.
I just found that with 3 cats, sometimes one is left out. how old is the kitty you have now? will you be getting both new ones at the same time?
I really don't mean to scare you, but I've learned that just getting cats and putting them together can take adjustment.

*only* 2 cats can also be a problem at times, yes, but I have had 2 cats, and then had 3 cats, and now I have 5, and 2 is different than 5. when there is 2 they usually play together and are not a problem, but like I said in my first post, the more there are, the more chance of one or another wanting something!