its not 100% accurate, some time and sales prints are 'duplicated' meaning vol is not quite accurate.
sometimes you get 460 contract print, then a 390 and then a 70 (both add up to 460). so you get double vol sometimes (i saw this on eurostoxx) its weird.
i only realised this when i opened an IB live acc and noticed different volumes.
apart from this the data is good, and there is nothing wrong with the price data.
you get a 2 week trial only, but you can *cough* get a new email address each 2 weeks and then...