For me, too much of the benefit comes from the conceptually dubious "journey ambience" but even if you take that out, the benefits still exceed the cost by a long way (4.4 instead of 5.1). Most of the benefits come from two sources: physical fitness and reduced congestion.
But the most interesting thing about it is that some of the schemes covered by the analysis are self-financing solely on the basis of reduced congestion. The value of the benefit from reduced congestion is as much as, or more than, the total cost of the scheme (see below).
If you were looking for a car-friendly justification for cycling infrastructure, you couldn't get much better than reduced congestion. And if it pays for itself, and helps the Government meet some of its own targets (see it's Reduced Traffic Congestion national indicator here) so much the better.
Value of reduced congestion as a % of scheme costs.
Birmingham 28%
Bristol 211%
Cambridge 97%
Leeds 46%
Manchester 166%
Newcastle 37%
Norwich 11%
Oxford 0%
Overall 105%