I'll be following this one with interest.
The problem for me is that I don't really understand the concept of "dark energy" (does anyone?), and the statistical analysis presented is WAY beyond my level of comprehension, so I'm totally reliant on the popular scientific press to get an interpretation that I can comprehend. (And I'm by no means certain that the modern popular scientific press is up to the job of understanding this sort of material!)
From what I have read, the analysis presented in this paper downgrades the likelihood of an accelerating expansion of the universe (based on analysis of Type 1a supernovae) from 5-sigma to about 3-sigma. E.g. see
http://www.ox.ac.uk/news/science-blo...E2%80%93-or-it
As I understand it, 5-sigma is the "rock solid gold standard" for statistical correlation (one in 3.5 million chance that the observation is a "fluke"), while 3-sigma is still "pretty darn certain" (99.73% probability of a meaningful statistical correlation.
http://www.physics.org/article-questions.asp?id=103
https://en.wikipedia.org/wiki/68%E2%...80%9399.7_rule
I think it's probably too early to dismiss the current "standard model" of an accelerating expansion of the universe driven by "dark energy" - even though that very concept is mind-boggling to me!