My daughter is 25 months and we've been potty training since she was 18 months! She is doing pretty good and will now go for longer stretches of time (a few days) without an accident. She still sleeps in a diaper but where's a "pull-up" during the day.
I'm now working on potty training my third child and have never found it difficult since I don't worry about it and don't force it. Kids figure it out sooner or later, and if you don't pressure them (IMO) they are more likely to get it sooner. As the saying goes, all kids are potty trained by the time they get married...if not, that's their spouse's problem :-P
My first son was a breeze, completey potty trained by 26 months. My daughter was a little more difficult, and slept in a pullup until she was almost 3 because she would have accidents at night. Now, Im working on the twins, who are 25 months. I didnt start early with them, because I figured they would let me know when they're ready. My babygirl is ready and I need to start putting her in underwear because they go to daycare and they wont train them in diapers or pullups. They go cold turkey. But her twin brother has no interest at all, and Im not going to push him right now.