most of the cheap 7inch ones are just gimmicky web browsers and have very little other use and the screens and keyboards are too small to really be usable.
8/9 inch ones are OK if you have the money to get a atom based one and can put up with the still smallish keyboard and screen
In my opinion the 10/11 inch ones are much more usable and not a lot harder to carry about.
It will be hopeless for editing photos.
You will be scrolling across as well as up and down for documents and internet. It will drive you loopy in a very short while.
Keyboard very very cramped.
The exception is the top end Sony which is very expensive but does have a good keyboard layout and screen resolution, but I still would not want to use it for more than half an hour at a time.
10" is the minimum I would consider. Be careful too if you intend using it outdoors. If the screen is glossy it will be reflective and impossible to see in sunlight.
thanks.
i have small fingers so hope i'll be ok in that respect...the photo editing would only be in an emergency i think, as id do most stuff on my laptop beforehand
this would more be to keep in my large leg pockets on set, so its always to hand as a reference with all my necessary info on it...etc