Loads of people have used them! :)
With DS1 I cloth nappied from about 8 weeks (moved house when he was 7 weeks and thought probs best to not do everything at once
), used terries in the v early days and then moved on to Birth to Potty pocket nappies (generally Charlie Banana and Little Lambs), as I saw them as the most cost effective choice.
DS2 is due in November and I'm doing sized fitted nappies this time, with prefolds/terries/muslins to start with. You get a better fit with sized nappies, whereas Birth to Potty can be gappy and a bit more bulky and temperamental.
There will be times when the baby is growing and the fit goes out the window, then the next week it will all be fine again etc.
You will need to keep tweaking how you boost your nappies - we started with whatever inserts the nappies came with, to microfibre plus bamboo, to microfibre on top of hemp, then to disposables because the cloth nappies couldn't cope. Now disposables can barely cope, he is a massive wetter!
Some good resources:
The Nappy Lady - if you live nearby you can go to her house for a fitting, I did :)
clothnappytree.com - basically one woman who runs this site and gives loads of advice, she'll always reply if you post a question. Good classifieds.
See if your area has a cloth nappy library/'nappuccino' - I ended up being given a lot of nappies to keep for free through mine.