I'm responding in a looking back sort of way as our dc are 30 and 27 now.
The big negative
Do not expect things to work out as planned and have a cushion. I went back to work (p/t) when ds was 4 months old. That was the compromise for part-time. No local family so he went to a day nursery - an excellent one. At 5 months he had bronchiolitis - a week in hospital, at 6 months pneumonia another week in hospital. He was wheezy and asthmatic and we had five hospital admissions in his first year. Ear infections started at 8 months : two a month until he was grommeted at 16 months. I resigned when he was 13 months and I left him at hospital at 5am to catch a flight for work (my dh took over). Funnily enough he seemed to turn the corner as soon as I stopped and he was grommeted!
I was lucky because we could manage on just DH's income although were down to brass tacks for about 18 months. Overall though, 7 years of p/t earnings £250k, loss of pension contributions and promotion potential, getting off the merry go round and having to start all over again.
I went back 7 years later and locally
The positives:
Pension
Self esteem
Dodging the school gate and volunteer requests
An income and greater financial independence
It made the DC more independent and responsible. If they forgot their instrument, homework, kit, etc, they had to suck it up because I couldn't float about like a fart in a bottle dropping off lost stuff.
Provided the DC with a more relatable parent.
Made me more relatable to DH and others as I had conversation beyond the DC, lunching, tennis, shopping.
There were only so many times I could make the oven sparkle and it didn't speak to me.
The DC seem to appreciate having an independent mother who understands work and can advise. As do their partners who had no such thing - see comment about schools, shopping, etc.
At 64 I'll retire soon on 75% of an occupational pension and full state pension. But, due to working locally and public sector since 2003 my overall earnings took a hit.
Hope that helps. I appreciate I was very lucky.