From Al Strachan of Fox Sports:
The idea was that the small-market teams would get some of the revenues of the large-market teams and thereby be allowed to compete. But there are flaws in that system.
For instance, in order to qualify for full revenue sharing, a team's revenue must increase faster than the league average and certain attendance levels must be met. But how can you meet those goals without spending more on players? Fans won't come to see a struggling team.
Read more Strachan's entire article here.
Strachan doesn't like Gary Bettman and never has, so his objectiveness may be called into question. That said, he raises many valid points in this article and makes a convincing argument that the system really hasn't accomplished what it set out to do.