You will need to consider the BizTalk Services edition required for your production use as well as the environment for test and/or staging purposes. This depends on decision points such as:
Expected message load on the target system
Capabilities that are required now versus 6 months down the line
IT requirements around compliance, security, and DR
The list of capabilities across different editions is outlined in the Windows Azure documentation page at http://www.windowsazure.com/en-us/documentation/articles/biztalk-editions-feature-chart.
Note
Note on BizTalk Services editions and signup
BizTalk Services is currently available in four editions: Developer, Basic, Standard, and Premium, each with varying capabilities and prices. You can sign up for BizTalk Services from the Azure portal. The Developer SKU contains all features needed to try and evaluate without worrying about production readiness. We use the Developer edition for all examples in this book.