There are two things I consider when buying a toddler swim pool. First thing I would consider would be the depth of the pool. Thesecond thing is, who best to limit acess to the pool.
Decide if you want a pool that can grow with your child, or opt for an inexpensive pool that you can discard when he outgrows it. Definitely teach your child to swim no matter how deep the pool, and never leave a child unattended in a pool.