No, I haven't seen it, but I read over a description of it and it seems a little lacking in drive. Correct me if I'm wrong, but from my understanding it seems to be a lot of battles, and, in my opinion, that isn't what makes Gundam unique. One of the best parts of the Gundam series is that it manages to mix drama, espionage, and plot into various conflicts. The upside for Gundam Battle Fighters is that it wouldn't require a lot of knowledge about Gundam and that it could be in more of a casual setting. On the other hand, if you go with something that's set in an actual timeline you would be able to introduce a lot more plot devices, and if you use certain timelines you could still keep the required info down (maybe omit some characters, similarly as to how Supervegeta and Raikiri are doing with One Piece). Ultimately it's your decision, but it seems like a slippery slope for Build Fighters.