Just completed 2 legs on Regiojet, leg 1 Prague-Vienna and leg 2 Vienna-Budapest. Leg 1 was on Business class and Leg 2 was on Relax class.
Prices were very reasonable compared to the competing Railjet options hence why the premium seats, the extra space was much appreciated.
An issue though was the lack of luggage racks in the premium cabins, we managed to fit our US style checked luggage on the over head compartment but some folks had to leave their luggages by the space next to the toilet.