What is hype? Hype is the promotional publicity of an extravagant kind. Brawl is hype. Nintendo has hyped up Brawl to the maximum, and I believe that it will pay off. Brawl has been atop the Japanese charts for 4 weeks (only just recently being bumped down by Dynasty Warriors Gundam), and I have NO REASON to believe that it will be atop the US Charts for a long time.
Back to the hype standpoint. There are more pros than cons regarding the hype of Brawl. One of the big methods of hype was the DOJO. The DOJO was a great resource to check everyday and surely brought up the hype of the game.
Other than the DOJO, a lot of the hype was brought up by all the fan boards out there on the interwebs. A lot of that is negative, but some is positive.
I really can't say if the hype will help the release or not, but once the game comes out at 12:01 on the 9th, we will all know.
Here is a Boss Battle Mode movie from YouTube. (Just in case you cared.)