a) If you are familiar with linux, it is as easy as configuring any other web server from scratch.
b) Maintenance is significantly less. AWS is a managed solution; you look after your software and data, they look after the infrastructure and data centre.
c) EC2 processing speed is as they promise, and is burstable. You can choose how much CPU you want access to. Latency is very good; you take advantage of a very well peered network. Extra services such as cloudfront can significantly reduce the latency for your visitors.
d) With regards to reliability, we have been using it for nearly a year in mission critical applications and have had no issues; compared with other services we have used before, this is the most reliable. You can set up your use of AWS in such a way that it fails over between data centres, so that even a data-centre wide outage would not affect your application.
Compared with all other services, AWS is easily the most advanced cloud computing environment available.
I cannot compare it with Rackspace, but for non-highend applications, it may simply be a matter of preference.
AWS has a free tier which I encourage you to try if you are curious.