I needed to move a 4.5 kg & a 18 kg package - Royal Mail wanted £25 for the two - but as it was during the time of their strikes, I couldn't be guaranteed of it even leaving the Post Office. I'd seen the reviews on Parcel2Go & was concerned about the item being collected. However, as the DHL depot is nearby (so I could drop it off there if needs be), I thought I'd risk it. I booked it at 23.49 on the Sunday evening, it was collected by 16.00 Monday eveing & delivered by lunchtime Tuesday - with no damage. The bonus was it cost £10 less than Royal Mail & I did'nt have to queue & listen to Mrs.Smith telling the P.O. girl all about her corns!!!
I can see the disadvantages of using this sort of service, you're dealing with a middleman - saying that, I used their Live Chat to confirm the details & found no problems with it. I can imagine that having to wait in all day for a collection could be a pain - bear in mind that companies such as DHL are primarily a business to business service & will be collecting from companies who have receptionists, warehouse staff, etc.
All in all - I would recommend it, but only if you don't mind hanging around all day - or live close enough to a depot to drop it off.