"What Microsoft did was take the .NET framework and VisualStudio and put them in a cloud environment; it looked the same, felt the same and the apps people ran looked just like what they'd run on their own [machines]," according to Margaret Dawson, vice president of marketing and product management for Hubspan, whose service has nothing to do with Azure, but has been doing cloud-based application integration for a lot longer than most cloud-service companies.
Easy or not, a lot of cloud customers -- especially those who want to put up systems more demanding or complex than a .NET app -- usually want some control over how they use storage, I/O, memory, processors, network bandwidth, security and all the other inconsequential support systems they're accustomed to being able to use to secure, stabilize or tune the performance of applications in an on-premise data center.
For that, they had to go to an Infrastructure-as-a-Service (IAAS) provider such as Amazon that offers not an abstracted execution environment, but direct access to all the data-center infrastructure systems. That access allows customers not only to run applications, but install their own virtual servers, choose among a variety of operating systems, and run applications in ways similar to running them in a data center of their very own.
Unfortunately for Microsoft, Azure and Amazon's EC2 have become the poster children for public cloud, which highlighted the advantages EC2's IAAS offers to people who really want to get down in the guts of the systems on which they run their apps.
Aside from more granular control of resources and infrastructure, EC2 lets customers run VMs with a variety of operating systems -- Windows, Linux and MacOS, primarily.
Azure's new VM offering doesn't go so far as to support "alien" operating systems like those last two.
It does let customers peel away one layer of abstraction between the software they're using and the metal on which it runs, though. Whether that's a good thing or a bad thing depends on the volume of guts you feel you need to wade through.