I work a 4 day week, currently- I find it fantastic. The working week flies- like a lot of jobs, I end up doing the same work in less time but I love being very busy. I think my work has improved, I am more focused, have more energy. A day off a week gives me time to reboot, reflect and often I come up with ideas on my day off that I'm not sure otherwise I would have.
I'm not sure that with a 1 year old and a 3 year old you'd get much done on your day off if they are not with the childminder though! But mine are at school now so I get a morning to myself, once a week when I get loads done. Laundry, cooking, cleaning, hair dressers, I did the couch to 5k running programme which I otherwise would not have done, gym, doctors appts, I do some writing, sorting out the bills, things I would otherwise find it hard to fit into the week. It also means weekends are less frantic and the whole family is more relaxed.
I'd highly recommend it on a personal front. The only drawback is that if you work a 4 day week I assume your holidays will also be cut- so bear this in mind before you make the decision.