It's actually a good size for me since I have tiny handwriting, but the issue I have is the turnlock doesn't lie flat when open, so I don't have a flat writing surface. I make it work though, because I still love it. Its size makes it very portable.
I do have a filofax (standard size, 6x8) which is more useful and customizeable but I rarely carry it in my purse due to it's size.