Avatar's been good. You do have to handwave that kind of ending as 'kid's show' but there's also the supernatural aspect to the show. The real Painted Lady showing up...maybe the river spirit couldn't act until someone had stopped the ongoing pollution?

I do hope E-lizabeth/Elizabeth 2.0 comes back...it would really be interesting to have her return as a villian, or a new ally, in control of the replicators.