I've got the version that comes with Cakewalk's Guitar Tracks software. As far as sound goes, it is incredibly good. I haven't heard any samples that compare to it. The thing that it lacks is ability to customize sounds. Since you are dealing with loops, you have to use what you are given. Whereas, with software like Fruity Loops, you can create a completely customized sound. However if you don't know much about drumming then there will be a lot of time spent with trial and error. I'd say that if you aren't comfortable with drum machines, drag and drop might be good for you. I definitely haven't heard any samples for programs like Fruitloops that sound as good. One thing you might want to check on before you buy it though is ability to adjust the tempo. The version that I have doesn't have all the features of the full version and is basically a demo. You only have a few choices for what tempo you want to use. There have been several cases I have encountered where the tempo was just too fast for what I was playing regardless of what loop I used. I really don't understand why they don't let you just set the tempo to whatever number you want. They may in the full version, I don't know.
