They will not perform tricks, talk, or perform heroic deeds. They don't eat pizza either. Some turtles like to have their head or shells stroked, but most of them don't like to be held or touched. Water turtles are primarily a look-at pet. Turtles live 40 and more years.
Turtles grow throughout their life.
A slider needs at least a 20 gallon tank to be happy, and a bigger tank is better. Outdoor setups are about the size of children's wading pools. It takes about 1 hour a week to thoroughly clean the enclosure, and about 10 minutes a day to feed and observe your animal. This is not counting the occasional visit to the vet. Food will cost 10-20 dollars a month, depending on what you are feeding.