Okay, the main negatives are that it is not very flexible. So you will have to be at school for the before school meeting - that usually means putting your child into a breakfast club and many schools expect you to stay around for at least a bit after school - to be on call if parents need to see you etc. You can't expect to run out of the door at 3pm. So you will probably need to have after school care, unless you are able to go secondary and work part time , but these hours are very rare and usually you have to prove your worth first before you get the cushy hours! (At least, that has always been my experience). Also, you are not entitled for paid time off if your child is sick. And as you haven't got any holidays you can use, if your child goes down with chicken pox and you need a week off for example, you will lose a week's pay!
Further, you are not entitled to any days off at all, so if your child has an assembly, sports day, nativity play, teacher training day and so on... you may be allowed to take that as time off unpaid, but don't even bank on that. If you do go into teaching don't expect to ever see your child in their school assembly or whatever. If you do, it'll be a bonus, but I wouldn't bank on it. Also, be aware that if you work in a different county or school your holidays might actually be different to your children's. I finish for summer two weeks earlier than my children, go back to work one week earlier and do not get as long for half terms. So I need to cover those times.
Also, you will be expected to go in for evenings when you are expected - open evenings, parents evenings and so on... you have to work around the school, and that's final really.
But, aside from that, you do get the school holidays, and you are able to take work home with you and do it in the evenings, to help fit around the children a bit more. I do most of my planning and marking at home.
I teach in a 6th form college, and now work mornings. I do condensed hours, so I don't get as many free periods as I should have - I do that work in the evenings. But it has taken me many years to get a timetable like that, and often I have had to work timetables that do not really suit me, but I have to fit my hours around the timetable. But, now I've been there a few years, I do get a bit of slack, and they let me have time off for nativity plays and the like, but I regularly do over and above the call of duty to earn that bit of slack. It usually takes a few years to build up that good will in my experience.
But, teaching is the best job in the world, and I am very lucky to have a job which I have been able to organise to maximise the time I spend with my children. For me, I have now got a timetable and job that works, but it has taken me quite a few years to get there. (And a couple of schools too - as some heads are far more flexible than others!!)