We're currently looking at using the Force.com platform as our development platform and the sales guys and the force.com website are full of reasons why it's the best platform in the world. What I'm looking for, though, is some real disadvantages to using such a platform.
Here are 10 to get you started.
Disclaimers/Disclosures: There are lots of benefits to a hosted platform such as force.com. Force.com does regularly enhance the platform. There are plenty of things about it I like. I make money building on force.com