Ok. I'll start out by saying I have a total of 8 packs of these tiles, so I'm obviously dedicated to using the york flooring.
The soft bounce the tiles provide is perfect for light weight work, and adequate for step aerobics and working out in front of your gaming console/dvd player/bluray device. Even skipping becomes easier.
Here's why I didn't give a fantastic score.
1. The cutout lines and sizes aren't 100% the same from set to set (buy three to four sets, and the odds are you'll be left with one set of tiles that doesnt quite fit). The result is that once you lay it all out, some joins wont lie flat to the floor.
Joins not lying flat leads to joins breaking mid session, leading to the user tripping up. A frustrating affair at best,injury causing at worst.
2. When pads are used as a support for cardio workout there's a tendency for them to slide around quite alot. Stops have to be put on all for sides of the mats, otherwise you end up chasing them around your room.
3. Get sweat on the mats and they WILL soak it right up making them VERY SLIPPERY and caution is to be used. Personally I keep a mid sized towel handy for when I need to floor work.
Having highlighted those negative points I would still prefer these tiles to many of the alternatives out there. But before you buy you should consider getting a RUBBER mat.