My 6th form nephews were amongst the marchers having travelled all the way from Manchester to take part. They are terrified at the debt they will have by the time they leave University and the lack of job prospects when they do, together with the cuts in Public Services in the meantime.
Even if I understand the financial problems the country is in, and I'm not sure I (or anyone else) does, I'm sure that many of the marchers don't - and simply see the impact of Government action on them. Can't say I blame them for protesting. If it leads to the Government doing a better job of educating the public as to why it is necessary to put up fees and cut jobs now when it was possible to conjure up mega bucks to keep well paid bankers in jobs a year or two ago, then the march will have done a great job IMHO.
That said, I don't in any way condone people who go out of their way to cause criminal damage and trust they get what they deserve.