As a bridge between Build Fighters and Build Fighters Try, this certainly goes through the motions of connecting the old series to Episode 1 of the sequel, but it does little else. If you've ever heard of Build Fighters, you've probably heard the criticism that it's "just mech fights," and, although there are copious mech fights, that's not exactly true. The first series was also a loving sendup of Gunplay culture and Gundam itself, often taking time to make fairly esoteric jokes just because it could. Try downplayed that element of the show quite a bit, and this ONA discarded it entirely. It's a very mechanicalstory that serves to get our old heroes together, gives them a villain, and then puts them in a gauntlet of mech battles, after which it ends.

Good thing I personally like mech battles, because this will be very disappointing for you if you're looking for something more.