We're using it in a big telecom. We have it in production for 2 years and we're continuing adding bundles now we have about 110 bundles.
Operation guys are delighted for the fine control this give to them: they can start stop single functionalities and monitoring them. Theoretically we could also hotdeploy a new version in production, but in the reality we use that feature only when doing test and preprod.
Our broad brush architecture is based on this one: http://servicemix.apache.org/home.html
Our main problem is always try to use standard java framework within osgi. The second problem is the bundle import/export management itself. We're using maven plugin.
All in all we're happy with this choice but you need to consider 2 things:
1. are you willing to fight with any java framework you want to add?
2. are you disciplined enough to not mess up your dependency?
