@userabuser yeah, it's pretty good. You could also look at carbonite / crashplan - they do something similar, but I'm pretty happy with backblaze. It's purely for data though - doesn't let you back up system files, etc
@anu Read a review from a guy who used both crashplan and then backblaze for a significant enough period, he pointed out some pretty decent shortfalls which were good to know but other than that seems pretty good, for data only is fine, I have other mechanisms for restoring OS and critical tools from images.
@userabuser yeah, I use it as my backup of last resort - offsite, data will be available if something really bad happens. For day to day use, I generally rely on Time Machine and bootable image where necessary