I joined a couple of years ago and my kids still love it! There are always great toys to borrow and my 5yo is really into trying different board games now. We hired a party pack of outdoor toys for my son's 1st birthday party and it was great for all of the pre-schoolers who were there, not just the littlies, kept them busy playing for ages.
Kids get so tired of their own stuff, so it's great to be able to swap toys every few weeks and try new toys you just can't get easily in the shops, plus they look forward to going and choosing new toys to play with.
I'm very happy with this toy library.

Approximate cost: $70/year