not really better than SAI as a whole, but has couple of huge advantages over SAI! the user interface is one of them!
beside I have an 7 years old computer, I have both SAI and sketchbook! sketchbook was WAY less laggy than SAI at 4k resolution. even though SAI only required a 12 year old processor (pentuim 2) and yet still whiny with a 1.2GHz processor from 2006!