I've got an A4 generic one. I find it useful for doing artistic stuff and fine retouching but most of the time I prefer my mouse. Mice have improved a lot since the early ones, the new laser mice with high resolution give a high degree of control.
Where the graphic tablet really comes into its own is when I'm painting and want different pressures or masking a tricky outline.
If you've got a program like Corel Painter then a graphic tablet is really fun.
Only when the last tree has died and the last river has been poisoned and the last fish has been caught, will we realise that we cannot eat money