1. The chuck that comes with it is a pain to deal with, so I had to buy another. That one was only marginally better.

2. The pump just doesn't move enough air with each stroke. As a result, it takes a LOT of pumping.

It's a pretty pump and it does actually put air into tires, but it's not nearly as good as the joe blow I bought for ~$35-40 to replace it. YMMV