I bought "Middleware and Cloud Computing" as a complementary book when I ordered the classic AWS book written by Amazon itself.
After reading both books I am convinced that Amazon has done a brilliant job!
But "Middleware and Cloud Computing" is a better choice for me because its main focus is on architecture and it mentions all known limitations of current cloud technology.
Both books are suitable if you are new to AWS, but "Middleware and Cloud Computing" explains the most important trade-offs that you are facing in real projects (EBS / S3 backed images, AWS Linux or other Linux distributions, Cloud Databases, SNS/SQS vs. JMS, software load balancers such as HAProxy or Amazon's elastic load balancing). The book also covers the second most important IaaS provider Rackspace including apps running on the Rackspace cloud, their REST API and their content distribution network Limelight.
There are detailed chapters about availability, scalability (AWS auto scaling) and monitoring.
It covers as well Oracle WebLogic server, SOA and Oracle Fusion Middleware including all the possibilities and options that currently exist when running Oracle products in the cloud. I never understood any of this from the available Oracle documentation (although I was spending many hours) so I especially enjoyed reading this part.
Overall, it is certainly a more objective book than the others I've read, explaining Amazon, Rackspace and RightScale together with plenty of third-party tools and their benefits.