Yes this looks nasty, because there are a significant amount of changes in extending your HSMP based on similar criteria for obtaining it in the first place. That is really scary.
While I was at the points threshold before, so depending on how thing were interpreted, the only thing that I even score points on anymore is previous earnings! I wouldn't even have considered this now. It is a dramatic change for some people.
Did you read all the stuff about document verification? Basically if they cannot verify a document with some "third party" entity that is going to be the clearing house for verification, basically it is the applicants fault, que sera sera! While in the "modern" world this is fine, this is going to be a nightmare for those non-first world countries.
Also the whole "Five Tier" Point System which will include study that they say will be implemented by 2007 sounds a bit scary as well.
It all seems as if this is trying to fix something that wasn't broken. Because of EU law, the UK is inflexible in being able to change some of the asylum and humanitarian "loopholes" that exist, as well as the people and process that are broken in the whole immigration machine, and instead want to make it more difficult for people who might actually contribute to the economy in the UK. It is the wrong fix for the wrong problem.