App engine has the following awesome characteristics: - the datastore is extremely scalable if you use it as intended. - your app can automatically scale up a

App engine has the following awesome characteristics: - the datastore is extremely scalable if you use it as intended. - your app can automatically scale up and down (as if an invisible genie were moving the little "workers" slider that Heroku uses) - always on instances make your app mega fast, even at low volume (but cost a tad bit more). - there are a lot of useful apis (memcache, queue, email) and a nice development environment. - it usually "just works" and "just scales". a few bad things: - they had some very annoying downtime while they sorted out the datastore architecture problems (where theory and practice had differed with horrible results) - the OSX dev tools don't bundle the correct version of python and associated libs, which makes it a pain to get a working dev environment on OSX without breaking your system's python. - no naked domains, SSL support for normal apps that aren't priced per user. All in all I'd rather write an app for AppEngine than any other cloud system, though Heroku is catching up -- both could really benefit from prioritizing 24 hour support via irc though.