Ranked in these QuestionsQuestion Ranking
Pro Allows multiple app instances
Limits are based on total memory allocation, you can allocate as much RAM as you want for each instance. Even the pricing is based on the total amount of RAM allocated, $0.04/GB.
Pro 24/7 live chat support
While it's true that AppFog may be relatively new and the online support is not very extensive, they offer 24/7 professional live chat support for any questions or problems you may have.
Pro Simple command-line deployment tool
AppFog has a simple command line utility to recursively push a directory to production
Pro Supports multiple data centers worldwide
AWS US, Europe, Asia, Rackspace, HP, Azure, and even Private Clouds.
Con Slow deployment
The deployment process with AppFog is generally nice and easy because of its CLI. Unofrtunately the only downside of that process is the fact that it takes too long. A deployment to AppFog genereally takes up to 40 seconds, which should be fine if you are deploying once a week, but when you deploy every hour it starts bothering you too much.