I have used Travel Up twice for business class tickets to New Zealand and Australia. Both times they got me a price that I couldn't get elsewhere, and in the latter case 2 x £2500 I class fares on Qantas on the direct LHR - PER flights that were proving very hard to find otherwise.
I'd recommend - I had a flight time change that took a bit longer and a few more contact attempts than if I'd booked direct, but I couldn't get the fare I wanted booking direct anyway!