Why would you want to play a retro game with all the nostalgic glory? Because it's damn fun, that's why.
Down to the basics. The story goes that the good guy Dr. Light has been framed for making 8 new evil robot masters, even though we all know the evil Dr. Wily is behind it all. So our Blue Bomber decides to set out and prove his master's innocence by going through 8 stages for each robot master. The 8 new robot masters are also awesome, each being very unique as always (for the most part). Every stage screams out classic 80's and 90's platforming, from bottomless pits to baddies that can knock you into a pit of spikes. Capcom definitely did not decide to tone down the difficulty of this game compared to the rest of the series, bringing back lots of easy ways to die if you don't know what you're doing. You will definitely not be breezing through this game on your first try, or even on your second or third.
The gameplay all remains the same, from Megaman's jump to the frequency of his arm cannon. This game could have honestly been made in 1989 and you would have no idea. This is exactly why Megaman 9 is such a huge success, and why it's one of my favorite PSN games.
While some spoiled gamers may say this is going a step back, I say this is simply staying in step with what gamers already know and love. Why fix something if it's not broke?