of course all babies are different and i have heard boys take longer to get the hang of the potty than girls but there does seem a lot of bad propaganda out there about early pottying. It seems logical that the earlier you get your child used to the proper way of going, the earlier they are going to not like going in their nappy (i use cloth ones) and will prefer the potty.
I don't know if the methods i use to make my 9 month baby happy on the potty (and help her remember to sit there long enough!) will work on a two year old, but you could give it a go...
Firstly, i never worry at her if she does go in her nappy, i know she doesn't like doing it and there's no way i would want to make her feel guilty. Same about accidental pees on the floor around bath time. I just say 'oh, well. doesn't go there! should go in the potpot!' and i make the potty sign. All in a cheerful manner though (i could have been on playschool me).
Secondly, while she's on the potty, we have mummy and baby time (or daddy and baby time if daddy takes her). This means that all the time she's one there we sing songs ('happy and you know it' is a good one), play clapping games, play peekaboo with a muslin (i put it over my head and go 'where's mummy?' and she pulls it off and there i am, time after time, it's amazing). Basically, loads of games which involve her hands (to stop her being a bit too interested in what's happening down there). Then she just gets up when she's finished and we have a quick look. If there's a result I say 'well done' and she gets a big kiss and if there's nothing in there I just say 'oh well' and that's that. We shut the lid and I get her dressed again.
*very good thing having a potty with a lid I'd say.
The other thing it's important to remember is that you have to be consistent. If she asks for the potty you /have/ to take her. Baby asked four times during one meal and there was something in the potty 3 of the 4 times and the other time she just had wind. It was unusual though to go quite that often.
At first I just pottied at home and nappied out and about but now that she knows how to ask for the potty I've bought one of those potettes and we're going to try our luck with that out and about.