If you have dismissed Microsoft as a cloud platform player up to now, you might want to rethink that notion. With the latest release of Windows Azure here at Build, Microsoft’s premier developer shindig, this cloud service has become a serious contender for the top spot in cloud platforms. And all the old excuses that may have kept you away are quickly being eliminated.

In typical Microsoft fashion, the Redmond, Washington giant is attacking the cloud platform market with a competitive furor that can only be described as faster follower. In 2008, Microsoft quickly saw the disruptive change that Amazon Web Services (AWS) represented and accelerated its own lab project centered around delivering Windows as a cloud platform. Version 1.0 of Azure was decidedly different and immature and thus struggled to establish its place in the market. But with each iteration, Microsoft has expanded Azure’s applicability, appeal, and maturity. And the pace of change for Windows Azure has accelerated dramatically under the new leadership of Satya Nadella. He came over from the consumer Internet services side of Microsoft, where new features and capabilities are normally released every two weeks — not every two years, as had been the norm in the server and tools business prior to his arrival.

Microsoft’s initial effort at differentiating Windows Azure centered around offering platform-as-a-service (PaaS) versus the raw virtual infrastructure-as-a-service (IaaS) play of AWS’s EC2. But this move, on its own, looked too much like lock-in. Over the years it has expanded the development frameworks, languages, and runtimes it supported and finally relented on IaaS this summer. It is now at the point where it can fulfill its claim that Windows Azure is Windows in the cloud. Frankly, if you can build it in Visual Studio and/or deploy it to Windows or to a virtual machine (yes, that means Linux), then it can run on Windows Azure. That doesn’t mean it should run in the cloud — that’s a totally different story — but the excuse that a workload couldn’t run on Azure seems, for the most part, to be gone.

On the cost front, Microsoft has been diligently following AWS pricing, although not in lockstep (that would make cost comparisons too easy). AWS had one up on them most of this year with AWS Reserved Instances, a discounting mechanism for EC2 that has quickly become the secret sauce for ensuring IaaS always trumps hosting on price. Well Microsoft, one-upped AWS this month when it released its Azure Commitment pricing scheme. Think of it as the cell phone minutes roll-over plan mixed with an all-you-can-eat plan. Where Reserved Instances gives you discounts on specific types of compute instances only in the EC2 service, Azure Commitment gives you a blanket discount on resource hours across all Azure services, including SQL Server and storage hours, plus higher level services like Azure Media Services and their MBaaS. And the plan can be purchased much more flexibly than Reserved Instances. This makes cloud consumption planning much easier and much more forgiving than the AWS plan (although the AWS Reserved Instance Marketplace is a bit of a buffer for planning errors on this platform).

If you have been waiting for your peers to use Windows Azure, that excuse is going away too. Microsoft said it now has over 100,000 separate named accounts using Azure, is adding thousands per month, and compute use is doubling every six months. If you are a government agency, an airline, a pharmaceutical maker, media company, a software-as-a-service (SaaS) provider, an oil company, or a financial services firm, your peers are already using Windows Azure. And our surveys of developers, development managers, and even I&O pros show Microsoft as a top-five most used cloud platform.

But you miss a lot of Window Azure’s value if you just look at it through the lens of AWS. Where Microsoft is differentiating itself centers around its integration with the on-premises world. From the beginning Microsoft saw Azure as an extension of Visual Studio and they were right with this approach as developers were pioneering cloud platforms, and they certainly had a captive audience. But the company has now integrated Azure with its Team Foundation Server that links teams of Visual Studio developers and applies life-cycle management to a normally chaotic, creative process. Now dev managers can control what goes up to the cloud, when, and for what purpose and can use Azure as a collaboration platform for diverse development teams. Earlier this year, Microsoft did the same thing for infrastructure & operations managers when it integrated System Center with Azure. Now you can deploy workloads to Azure, and IT Ops can monitor and maintain them using tools they already trust. And now that Windows Azure IaaS runs the same underlying OS (Windows Server 2012) and hypervisor (Hyper-V), you can suddenly, with confidence, have a complete hybrid cloud strategy using assets you already are using that share the same foundation and are designed to work together. And Microsoft’s acquisition of StorSimple should play a part in this story. Yes, I know your “private cloud” isn’t based on Hyper-V, but it isn’t really a cloud either — so that opportunity still lies ahead for both you and Microsoft.

Where Microsoft needs to work the hardest now is in evangelizing Windows Azure to its vast ecosystem of software providers who build applications for on-premises Windows server and client. If it wants to have any hope of competing toe-to-toe with AWS, it needs to bring as many of these partners over to Azure as it possibly can. This doesn’t mean convincing them to migrate their applications to Azure, rather it means helping them incorporate Azure into their business models. For client and server applications, this means App Internet integrations, where code in the cloud enhances the on-premises experience. For mobile developers, it means using Azure as their mobile back end. For some it will be transitioning their businesses to SaaS or exposing their software as a cloud-based service, but for many this wholesale move just won’t compute.

Of course, Microsoft should also appeal to the new generation of startups that are building fresh capabilities in the cloud, and its latest moves should make Windows Azure an attractive platform. But companies that build software for Windows today far outnumber the startup community, and they collectively represent a market opportunity cloud companies could only dream of tapping near term.

Both ISV audiences will benefit from the revamped Windows Store that makes it easier for ISVs to showcase their wares to all appropriate audiences in the proper context without having to work their way into separate stores for Windows desktop, server, mobile, and Azure. Developers can add app services like New Relic and AppDynamics, and data sets such as historical hurricane data from Weather Trends International, to their Windows Azure projects the same way they would add any native Windows Azure resource. Purchases can be made directly through the Windows Azure Management Portal. Good job.

There’s certainly a lot of work ahead for Microsoft to make Windows Azure a sustained leader in the cloud platform space. We’re only getting started in enterprise adoption of cloud platforms, after all. But the company’s hard work in making Windows Azure a credible place to put your custom applications makes them a credible first-tier competitor.