You can get the tickets at close to face by going to the Celtics ticket exchange. They go fast, but they are available. I know, 'cause I just had to post my tickets for the game (long story) and they were gone in a matter of minutes.
On topic - yes, it is not as loud as 2002, or anywhere near as loud as the old Garden. People haven't figured out how to exploit the building to make noise. I was beating on my seat in the bleachers at game 2 of this series to make extra noise, and all the people around me looked at me like it was such a new and novel idea...none of them joined in, by the way. I think that many people think of themselves as spectators, rather than as being a necessary part of the experience.
And I STILL want the folks in the top level to start beating on that retaining rail the noise we could beat out of that thing, if only we'd try...it would be amazing - for the love of Mike & Tommy, people, make some serious noise....