I dislike the Liberal Democrats, but I have to defend Clegg on the alleged 'oath breaking'. The Liberal Democrats did not win an election, so how could you possibly expect them to keep their manifesto pledges? They got the best deal they could out of a coalition and do seem to have achieved some policy changes.
It's ultimately the tuition fees thing that's the problem, isn't it? By and large, their supporters understand the rest. But you can't pledge this in your manifesto and not expect a backlash for doing the opposite:
Phase out university tuition fees within six years. Scrap fees for final-year students immediately. Scrap target of 50% of people going to university [England only]
There was no way they were getting to do that, but maybe they shouldn't have supported the change to the new system? I'm not sure. The changes were probably necessary - note that nobody is pledging to reverse them (apart from the Greens, but they seem to believe in money trees).