Hi,
I worked for Chatteris as an English Language Teaching Assistant during the 2003-4 academic year. I never had any problems with the organization; in fact, they provided the opportunity for me to begin my career in the Hong Kong public education system, a career that I now would like to kill, sooner rather than later, but that's another story!
Although I never had any problems with Chatteris, many of my colleagues did, and there was a ridiculous turnover rate, which, apparently, still persists to this day. There were many irreconcilable differences between the ELTAs and the management because, to make a most glittering generality, the Chatteris manager is a worst-case, stereotypical Han Chinese Hong Konger, mostly tyrannical, sometimes irrational - this gonzo management style is prevalent in the Hong Kong public education system.
Still, Chatteris is worthwhile because it will open doors for your career here in Hong Kong, and you will also meet tons of other good blokes. In the scenario that you do find the company to be hell, you can always quit and find another job - your visa is good for a year, after all!