I have a similar problem and I've read all the help I can find to no avail.
On my iMac (Mountain Lion), ipad1 and iphone4, notes synchronise perfectly I can edit a note on any machines and they all update over iCloud.
My wife's iMac runs Snow Leopard so doesn't sync by iCloud but she also has an iPad1 and a new iPad Mini both of which I've set to synchronise over iCloud. Everything else seems to sync OK but the notes on her iPad 1 have not appeared on the iPad mini - except for one new note. That arrived.
Any ideas? I'm probably missing something really simple.