I feel that it may be worhwhile for any prospective customers to understand fully the SUP/FUP policies that are in force at Plusnet / Force 9. Search for "Vision for 2006" - this details the direction the F9 ship is being steered in.
This details how your account is capped, traffic shaped and manipulated, depending on what you are doing
IF, you understand all this from the outset then you probably will not be dissapointed with the overall offering that F9 give. If you don't then you may find that you have signed up for a service that is frustrating and not for you.