Panniers are a standard fitting on the Pan and they're not bad at all.
They'll each swallow a helmet (my head is rather big, no comments please), gloves and waterproofs with ease although adding a jacket or boots becomes a bit of an exercise in efficient packing. They use the ignition key for the lock which is quick to use and (most importantly) is easy to get to. Note: That's each. When riding solo, the panniers alone can hold all my riding gear.
Removing the panniers is very easy. They are removed by using a simple lever release, again locked with the ignition key. Re-attaching them can be a little fiddly but never takes more than a minute or so.
When off the bike, he integrated carrying handles make it easy to tote the panniers about like a small suitcase. The unusual shape of the inside face means they can be awkward to carry unless you face this outwards. Then, you have to be sure that your trousers (or whatever) aren't going to scuff the visible side of the panniers.
Other stuff?? Well, they don't like being over-filled by bulky (as opposed to heavy) stuff and the lid seems to deform a little too easily, preventing it from closing properly under such pressure. They're watertight courtesy of a rubber seal which runs all the way round. Again, if you're packing them pretty solidly, you have to be careful not to interfere with the seal as this can prevent them from closing properly.
All in all, they're proving to be most useful. And have been much enhanced by the optional pannier bags I bought. These seem to be fairly rugged and, although they don't fill every last bit of the pannier, you can be sure that if your stuff fits in the bag, you can put the bag straight into the pannier.