Apparently, the success rate for appeal is low - usually improved if you appear or have an advocate appeal on your behalf.
They are trying to restrict the eligibility for these benefits in the current climate and I think that unfortunately far too many people who are not ill are using the system to their benefit by claiming mental health problems that they do not have - this means that those who genuinely need it are now being refused also.
For me personally, working was a good way to help me overcome my problems although I know it does not work for all.
Good luck