Tablets are debatable really. While yes they can provide better control something and lend more to your artistic style.
On the other hand artists have good & bad days. With a mouse you never have a bad day.. atleast no in my experience. Sometimes it is just easier to use the mouse for somethings.
Like I enjoy drawing details and getting things sorted with my tablet, but when I'm working on doing shading and highlights.. far far easier to do it all with the mouse. Just feels like there is more control. Photoshop reacts to both differently though.
With a mouse you have a set colour amount, intensity and size. For the tablet though the intensity affects the size. Often this can cause more problems.