We used them in late December. Their prices were the best we could find. Tickets took a couple of weeks to arrive. reasonable service.
However, at the time I didn't realise that Attraction Tickets Direct will price-match. To me, they offer better service and generally include some free 'extras' - e.g. free Odeon cinema ticekts last year. I think there is a thread on here where it mentions some free 'travel pack' they are providing this year.
My recommendation would be to call Attraction tickets Direct and ask them if they will price-match the price you have there.
Julie