I've been buying the League Pass for the past 7 years for Celtics games.
The broadband service is OK, but not great. It's definitely not high-def, atleast it wasn't the past few seasons. They do make improvements each year, don't know what new features we get this season.
Last year they added home and away feeds for most games, which is nice, because listening to other announcers can grow tiresome. They also added replays throughout the overnight. Two seasons ago they added an HD channel for one or two games a night, although the Celtics are rarely on that channel, especially home feeds. Three years ago was broadband.
My major problem is the SD feeds for all non-nationally televised games. Other than ABC, TNT, ESPN, NBATV, and my local market (NYK and NJN), the rest of the games on the League Pass are of horrible quality, atleast on a really good HDTV.
I've contemplated not getting it for this upcoming season because of SOOOO many national games, but I just can't miss half the Celtics games.
The broadband-only option is something you can definitely consider if you have basic cable and get the TNT/ESPN/ABC games.