All the original ruling stated was that it is illegal to automatically remove voting rights upon conviction i.e. that removal of voting rights must be decided separately from custodial and financial penalties. This is a tiny problem.
All this ruling does is tell the UK government that the European Court is not interested in the precise details but only that the UK fixes the issue from the first ruling. This can be fixed easily with a couple of changes to legislation and sentencing procedure.
However that's not going to happen because
- the press and the Labservatives have somehow managed to convince themselves that the ECHR has something to do with the EU;
- the public and many MPs have somehow convinced themselves that the ECHR wants prisoners to have votes:
...both of which are utter balls