I'm not sure if losing control of your key product is such a win in the long term.  At the end of 5 years, Airbus has the option to the full rights to the CSeries.

Bombardier might also have been able to get Airbus on board with 49.9% of the shares instead of 50.1% (considering Airbus didn't even have to put a penny towards the deal).

I wouldn't be surprised to see the executives at Bombardier give themselves another hefty bonus and raise out of this deal.