I've not used their service as I run my own hosting company. Other discussions I've seen for some of these very large offers does tend to suggest the T&C's can often be worded in such a way that they effectively prevent you from using any more than a traditional £5/month type of package.
Many newbies simply go for the biggest numbers for the lowest price without any understanding of what they actually need.
Many of my customers use less than 20Mb of disk space and less than 1Gb of monthly data transfer