We went a few weeks ago and had fun. It's kind of small, but for being free (or $1) it offers a few hours of entertainment! The surrounding park is great too. We also plan to check out the other St. Louis Park aquatic park sometime soon.
Cascade Bay in Eagan is nice too.
We have not been there this year (or last) but we want ALL the time the summer before that. It can get busy but I know Aiden LOVES IT.
Given were you live there is a free one in Apple Valley (kelley park), Eden Prairie (Miller Park), also there are some there is a pay in Edina (Edina aquatic center).