I've used graphics tablets for the last four years for all design and photoediting work.
I've only been able to afford the small cheap versions 5" x 4" Genius at about 30 pounds sterling.
I had a few problems when I started due to not having the software installed properly, but I've had not a single glitch since.
If I have to use a mouse I find them fine for browsing in conjunction with the keyboard, but if I'm drawing, I find the natural movement of my hand using the pen much friendlier.
Because I never learnt all the keyboard shortcuts, (I've always used pc's not macs) I find using a pen controlled cursor quicker. It's very much a personal thing, I think, and probably depends on your own experience which way you go.
I've never tried a large format board so I don't know what their advantage might be, but I'd definitely recommend trying out a cheap small tablet - you may never go back to a mouse.
It's like doing jigsaw puzzles in the dark.
Enjoy today's problems, for tomorrow's may be worse.