There was an interesting discussion on the ServiceMix users list on how to choose between implementing integration solutions using ServiceMix or camel; thought I'd post my contribution to that discussion here. ServiceMix should really be thought of as a container, that facilitates the deployment of JBI-based integration solutions and Camel-based solutions for enterprise integration. And, of course, ServiceMix 4 is an OSGi container, which extends the concept of what can be deployed - JBI service assemblies, spring configuration, OSGi bundles, etc.
The question really becomes "Should I use the ServiceMix JBI components (-eip, -file, -ftp, etc.) or should I just use camel components?" I think the decision around this will depend on whether the JBI architecture forms an important underpinning of your solution: if so, then it makes sense to use the JBI components. If, however, you have no desire to go down the pure JBI route, then you can choose to adopt either a pure Camel or a more blended approach.
As Chris Custine and Jean-Baptiste have both pointed out, Camel integrates very effectively with JBI, so you can get the best of both worlds. You might find that the JBI servicemix-ftp component is more robust than the camel-ftp component, and choose to use the former as part of a Camel route. Or, you might prefer the servicemix-eip Aggregator's persistence of state over that of the aggregator in Camel.
So: my advice is, in a nutshell, move forward embracing a blend of both JBI and camel components, and, consider 'ServiceMix' to be a container for both.