I am currently in my second year at saw mill, while it does not necessarily carry the cheaper price tag as some other halls do, the rooms are generally ( from seeing multiple other flats) quite good condition as everything only opened last year (2014)
Internet speeds are quite good with an option to upgrade for £90, however, as someone who's course requires him to be watching plenty of on-line content, along with constantly downloading different pieces of software, I don't think this is necessary in the slightest. There are instances of course where the network might go down but unite are incredibly fast at fixing any issues relating to the INTERNET or any other concerns with your flat.
In short - for a first year wanting some of the nicest accommodation around- It is definitely worth it. However in second year, I would recommend getting a cheaper place as the higher cost comes with a sacrifice on food budgets etc.