While I'd agree Python 2.5 to 2.7 doesn't bring a swath of language features with it... it's a good sign of Jython's slowing/sluggish growth/development.
Personally, I want to use a language implementation that will be around and (well!) supported for many years.
It seems common that people don't upgrade to a breaking version of a programming language based on name or distro channel alone. Hence the slow uptake of Python 3 and Perl 6.
Personally, I want to use a language implementation that will be around and (well!) supported for many years.