We used this service three times on our trip which saved us a bundle on extra bag fees.
We left a large bag at Excess Baggage Terminal 3 when we arrived from LA with all of our cold weather clothing. We went to Marrakech for 4 days and picked-up our bag from storage and and unloaded dirty clothes and picked up our gear/clothes for our safari to South Africa. We then put the bag right back into storage. After 5 days in South Africa we returned and got our stored bag. We got our cold weather clothes out and put our safari clothes and souvenirs into the bag and back into storage.
When we returned to LHR this morning after 3 days in London we picked up the bag again and rolled it to checkin and now I'm sitting in the lounge.
It was so much more convenient and secure to leave a bag at the airport terminal that we had to transit anyway.
What made it really neat was packing the clothes in separate 2.5 Gallon Ziplock bags with a destination description written on each with a Sharpie. So when picking up the bag it was a quick and easy transfer to the suitcases that accompanied us to each location.
I will use them again next year!
Steve