The only reason I played the MMBN series was because of the MMC references; star force is a stand alone series, with no relation to MMBN even in terms of storyline... the "Megaman" in the game came about rather awkwardly.
Old MMBN series had better game play in general, and it had plenty of side quests for you to indulge in afterwards (which I enjoyed, since they were all basically to do with unlocking secret bosses from the MMC or even MMX series)
I recommend you save your money for MMZX:Advent (which I already have; and is extremely fun) if you actually want a Megaman title true to its nature... this new title offers little to new gamers, and old fans of the series don't really enjoy the new system... it really sucks...