I bought these Easy Ups Trainers as the transition for my 2yo (who only weighs 26lbs) but she wasn't able to pull them up and down herself and I found them difficult myself.  This resulted in frustration for both her and I.  They also don't have flaps for easy removal if an accident does happen, thus, the only thing to do is to rip them.  Not the easiest thing when there's a big mess and you're in a department store bathroom.