Great story, but difficulty takes terrible extremes from annoyingly easy to impossibly hard.
The story is excellent and for that I enjoyed the game. The rival Navis were interesting and the plot was full of light hearted fun and seriousness and even betrayal and deceit. You once again take control of Lan, the operator of the Net Navi, MegaMan.EXE, as together they take on Net Crimes with their awesome virus busting skills.
The basic controls of the game are the same as the previous installments, 3x6 grid where each side starts with a 3x3 grid to themselves. Lan sends MegaMan.EXE battle chips with which to delete his opponents and certain combinations create Program Advances. New to this installment is Giga Chips and Mega Chips. Several chips have been "nerfed" so to say by becoming Mega Chips. All this means is that you can now only place one of that type of chip in your folder. A Giga Chip however has the same limitation but also cannot be traded. Also new to this installment is the Navi Customizer, which at the same time, eliminates PowerUps. The NaviCustomizer allows you to do what you could with PowerUps, but also allows you to use special programs such as one that always leaves MegaMan.EXE with 1 HP after taking an attack that would delete him so long as he had 2 or more HP or one that automatically sets the panels in every fight to a certain type or programs that add 100, 200, or even 300 HP to MegaMan's total HP.
Now to explain the downsides of this game. This game can be divided into 3 parts for the annoyances. The first annoyance is that you spend the first 3rd of the game running back and forth through the same areas over and over again to progress. The second annoyance is the second 3rd of the game where you spend your time mindlessly battling random viruses trying to get specific chips. The third, final, and most annoying part is how you spend the remainder of the game fighting impossibly hard battles back to back to back to back (literally, there's one part where you fight several Omega viruses per battle in four battles in succession.) And to top off all that, the boss fight consists of 2 fights as per the previous installments and the final fight is the toughest of the 3 games.
In summary, I wouldn't recommend this game to someone new to the battle network series, but for someone who has played 1 & 2, definately get this as the story is really good and is even better if you've played at least MMBN2.