No, 50 miles isn't bogus, but it was never claimed as more than a best case range. Over on the Ampera Owner's club a few UK owners have already got more than 50 miles range on a single charge. 25 miles does seem to be about the worst case, usually reported by journalists hammering the car for a review in the middle of winter. Typical range seems to be more around the 40 mile mark which is more than enough for a lot of people's typical commutes though oubviously it won't fit everyone.
Payback versus the Chevy Cruze is a bit of an arbitrary figure: the Cruze is a much lower spec car so why not calculate versus the car that most Volt/Ampera owners would have bought if the Volt didn't exist? The most traded-in car for a Volt in the US is apparently the Prius, but the main car to compare against seems to be the BMW 3 series. Cabin noise is a good one to compare: you can pay a lot of money to get a car that is as quiet as the Volt.