This is my first non-Canon lens and I only purchased it because I had an emergency and needed a wide-angle lens for shoot at the last minute. (The customer added some requirements a few hours before the shoot started.) I had been budgeting to buy the Canon L wide-angle but didn't have enouph money yet and even if I did, this was the only wide-angle lens available locally. I purchased it with the understanding that if I didn't like I it could return it within 7 days. After seeing the pictures it takes, not only is it not going back, but I stopped saving for the Canon L. I can't image the pictures looking any better and refuse to return this one. The customer loved the photos I took and I have taken a few others with it that have been very popular.
The detail is great, there is virtually no distortion even when I am close to the subject. As for speed, I live near a theme park and yesterday was able to take 4 pictures of one set of people going over an outside roller coaster loop and have sharp enouph detail in the photos to see the differention between the big toe and the rest of the toes for the people that rode barefoot when I zoom in. Considering the full shot not only included the full multi-story loop, but also foreground at the bottom and sky at the top, I consider that getting good detail. At the same park, I also took a close-up of a flower was sharp and colorful, and some glassware in a store that I really admired. I have to remind myself this is a wide-angle lens, not a general purpose one. The pictures it takes are so good that if you don't need the zoom, it can be used as a walking-around lens.
One last thing, it feel more comfortable in my hand than most of my Canon lenses. The material is just more skin friendly and there is very little weight compared to many of my other lenses.