I've noticed personally that some decks shuffle really well and others shuffle like sh*t. A deck that reads really well, shuffles badly, and because of that, I don't want to use it that much. I find it's too much like hard work because the shuffling doesn't "flow" well and cards keep shooting out. Shuffling to me is almost a meditation and plays an important part in the reading process.
Quite often cheap decks can shuffle effortlessly, yet more expensive decks are hard work shuffling. Some designers opt for larger, thick card stock which makes shuffling difficult.
Does anyone else have a similar problem?