Raising the retirement age to 66 will be unpopular but pretty uncontroversial, I think. Everyone agrees on the basics (people are living longer, the nation is bust, there is a massive black hole in our pension provision). The only dispute is when the raise is done.
The really controversial bit is companies not being able to impose compulsory retirement on people. That presumably means if they want to fire them they have to pay redundancy money, which could be very expensive, especially as redundancy is usually calculated based on length of service. You might get people unnecessarily holding on for the payout. I can't really see a good solution to this. I don't think you should be able to force people to retire if they don't want to, but at the same time if they are not up to the job because of age then it is a bit unfair all of a sudden to lump employers with this very costly extra requirement.