I'm a Candidate FIDE Master and I've tried the Scandinavian Defence, and Modern Variation, in the last 2 years. Against weaker opposition my results were very good. Black equalises easily, and quickly, and has very active pieces. The c4 move by white, taking the centre, is hardly a serious problem for the prepared player. After all, many defences concede the centre to white, only to counterattack it later. It is a concept introduced to chess 150 years ago by the Hypermodern School in chess, of which, Aron Nimzovitch was the chief exponent. Defences of this type are the French, the Pirc, the Modern Defence, the Alekhine Defence, and are all played by strong European GMs.
To say that the Scandinavian defence is inferior is laughable,but there is a small problem,in my opinion,to be honest.If you need to win on a specific game with black and face a good opponent,if as white they play very solidly,it is hard to obtain a promising position and the majority of games at higher level end up in draws. Black gets winning chances only if the players with white press too much for the win,underestimating the position.