The pricing is really cheap. Looking at the pricing of instances on EC2, I don't know how they get so cheap. I'm sure the answer is in the details if I were to go digging (different hardware) but it's cheap.
I don't think the Asure alternative will be even close. While AWS makes Workspaces easy and affordable for just about any individual, that person is probably still not the target for MS. I'm guessing this new offering is simply the same service as they already offer, for businesses which want systems for less than 100 people, and are still able to dish out a load of cash.
The benefit to Azure is that it's Microsoft. They aren't going to compete on pricing for anything. If pricing is your main concern, then you don't to Azure (or even Google Compute.) If your boss says you have to use Azure, then that's when Azure has the advantage. ;)
That's not a gigantic barrier if you're an enterprise, but figuring out licensing for Workspaces if you don't have a couple smart Microsoft admins and money to burn is really hard. This is easy, since all of the license entitlements are enforced through their portal. (if you can start an instance you are licensed)