Microsoft and SAP just announced a world record for SAP performance. Specifically "World Record for the category of SAP Sales and Distribution Standard Application Benchmarks executed in the cloud deployment type". It is a great endorsement for Azure and Microsoft. You can read more about it here:
Now, on to my point. Read through the article and you will notice a significant amount of detail on the planning and design. A lot of thought went into figuring out how to overcome the typical SAP performance issues in Azure. There was a lot of thought put into network and disk performance. The compute was carefully considered too. You might not control the network, compute and storage in an IaaS model but you sure as hell have to think long and hard about it. I would even go so far as suggesting you have to plan and design in more detail for the cloud. I have seen far too many projects crash and burn due to lack of technical planning. Be sure to know the scales, limits and constraints for the platform.
Don't confuse easy purchase of cloud services with easy adoption.
The image is from Mark Anderson www.andtertoons.com The devil enquiring about the details.