How easy would it be to get another well paid job in your field is the first thing I would ask because you have to give yourself at least the option of returning to work should it not work out for many reasons. Look into paying into a pension to protect that aspect too.
I have been a sahm for 20 years, initially due to a relocation with Dh's work and then permanently when I developed a health condition. How was it? It was the absolute best decision we made for our family, but I never had a career, I had a job with decent pay but not like Dh's career and he significantly out-earned me.
At no stage did Dh ever take for granted what I provided for the children and the house in terms of organisation, cooking etc. He was grateful that he didn't have to come out of any meetings that had run over to collect a child so was able to progress his career. We used to share nursery drop offs and pick ups when I worked.
Discuss finances honestly. I have full access to all accounts and can spend what I want when I want but Dh and I have been together almost 30 years now so we were aware of my spending habits before the sahm part and we trialled the sahm situation for 6 months to see how we both felt. Dh was raised by a sahm who did everything. I am fortunate that Dh was a hands on parent from day one.
The negatives can be, everyone bar one Mum I am still friends with returned to work either full time or part time so it can be lonely. The longer you are a sahm the more people return to work. It can also be very monotonous with day to day drudge of housework and child rearing. There is no annual leave, there are no sick days and it depends on whether your Dh would drop everything to look after his child should you be too ill to do it. You see it on here lots about men swanning off to work leaving their wives on their knees, she is an appliance, annoying when she breaks down and doesn't perform.
Other people don't respect your decision or role as a sahm. Some husbands let go of everything and literally just work. All the child stuff, parenting and any house stuff gets left to the wife because she is home all day. Some husbands also make it almost impossible for their wives to return to work, they expect the same 100% housework and child stuff from a wife working either part or full time. I have seen this in real life and been on MN for 18 years where this is often reported.
Go into this with your eyes wide open and if you do it I hope it works out for you. For both myself and my other sahm Mum friend it has been a complete success.