I have used two pairs of Agusport 550 Quorum for more than 20 000 km before retiring them this year.

I like:
* Small external pockets (perfect for small items or extra water bottles)
* Durable (only recently have small holes developed in the bottom)
* Water resistant, but I pack everything in plastic bags
* Securely locked to the racks

Don't like:
* Complicated way of fastening the lower end of the bags to the racks (I think they have replaced it now though)
* The rain cover goes into the top flap, so either one must use the rain cover all the time or when it rains the bag is not quite full (since the rain cover no longer takes volume) and the rain cover isn't tight on the bag
* It's too big to use as a front pannier (not the bag's fault..)

Since I have used them for so long I have apparently been happy with them, but I replaced them with panniers from Vaude (not sure of the model) this spring. I have only 600 k of touring with them but so far I like them. I'll tour a bit more with them later this autumn so I might come back with a fuller review.