In a word yes !

There are reviews out there, a look at the measured MTF figures will show it has more resolving power than the Canon. However that is not the full story, as we all know many factors that need consideration, not just purely virtually meaningless numbers on a graph. The colour , contrast and sharpness imho is better than the Canon 10-22mm. A particular strength is that chromatic abberation and flare on the Sigma are virtually non existant, not so with the Canon lens. To me this is a very important consideration when you will be using it to shoot scenes that will have a very high dynamic range.  

Match it with a set of z pro grads, a good tripod and you have the basic kit for landscape work.

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html