Well depends on what you call great as far as weather? The central valley (where Modesto is located) gets hot in the summer. It'll be in the mid to upper 90's most of the summer with some days well over 100. Hot but not usually too humid. Winter it'll be cold and rainy but no snow. Does get foggy.
I live in Tracy which is about 30 miles from Modesto. Can't really tell you much about the schools there except that CA in general is having MAJOR budget issues this year. Schools are having to really slash budgets and cut out extras.
The good thing about the central valley is it's proximity to a lot of great things. You are 90 minutes or so from Sacramento, and San Francisco. You are an hour or so to Yosemite. 5-6 hours from Southern California etc. Lots to do close by although I wouldn't say that there is a ton in most of the Cities themselves besides the needed shopping, restaurants, etc.
Houses are down now but CA is expensive. I know in Tracy that you can get into a really nice 2500+ SF house in the mid 200's right now. Modesto should be running down closer to $200K. Not sure if that's high where you are or not.
Good luck with the decision!