Just used the DVD for the first time and chose the 15 minute workout. My arms will definitely feel it tomorrow!
I don't have a high level of fitness and only just managed to keep up, but as I started with the 15minute that is probably my fault.
The only criticism is one I have seen other reviews make, there needs to be a better warm up before the workout, even if this was just another 5 minute section you could choose to do or not do prior to choosing how many minutes work out you wanted.
As the first fitness DVD I've ever bought I am very happy with my purchase :)