The Spark is very easy to get into, the UI is clean and transparent, the controller feels great to use and the included library is great. I found the presets a little lacking, but you can change and edit sounds to your heart's content. Ableton integration is a bit weird, but it's workable with a little patience. I have actually made complete songs just jamming on the standalone version and recording the output.
The Spark Le is a very good drum machine and invites you the first time you use it into a world of experimenting and enjoying! The preset sounds on it are good but if you choose to use own samples in addition you're going to love it. When you play with a drummer, make sure he is used to play to a click! Otherwise you're going to have a bad time ;-)