Definitely one of the biggest and most successful, yes.
Though, it's honestly hard to compare it to 2nd and 3rd gen because the game has changed TREMENDOUSLY with globalization. Physicals are blowing UP. People with flop songs are selling over 100k, which was out of the realm of what was possible even 5 years ago. Also, Melon has lost a lot of the monopoly it had over streaming and digitals from the 2nd and 3rd gen. Don't know if I'd say MOST successful, but maybe top 10? Possibly top 5? If we're just going by debuts.