Very good basket
Bought this basket two years ago for my Jack Russell puppy. Assuming my puppy would be bigger when she reached adulthood I bought a bigger basket as I was concerned about weight limits. Well, my puppy grew up to be one of the smallest JRTs ever and she runs alongside the bike now but I still think the basket is one of the best around. Yes, it is a bit bulky and it does take some getting used to (a few seconds?) but I managed alright with a full basket at the front and my daughter on a tag-along bike at the back--you get a few smiles as you go along. As my dog is so small, I often carry my rucksack, toys and coats as well. If installed correctly the bracket keeps the basket locked in position and has a very solid feel about it. It's very easy to take out the basket and put it back on. I also use a normal mesh basket when I don't need the doggy basket and the Aumuller bracket doesn't interfere at all.
The cage is also very handy (especially if your puppy considers it her duty to chase every cat she comes accross). Two years on I'm still using the basket occasionally when having to deal with heavy traffic. Poppy runs alongside the bike until we get to the more dangerous area, where I undo the cage straps, tell Poppy to climb up my leg (handy trick) and transfer her to her basket without any need to get off the bike; as soon as it's safe she's back on the ground again. For this reason, the straps have endured heavvier use than you'd expect in a basket that is not used that often and they're still in very good condition--worth noting as they looked a bit flimsy to me.
All in all, very good quality but bear in mind you will have a BIG basket in front of you when cycling.