Through having the choice of Megaman or Bass at the beginning of the game the developer has hidden an easy and hard mode depending on which character is chosen.
The GBA version as well as the Virtual Console version (an emulation of the GBA game) has large sprites (due to the resolution of the GBA screen) that make many parts of the game frustratingly difficult.
The game's weapons (Concrete shot in particular) allow for clever movement and attack mechanics useful for speedrunning, or even just for fun finding multiple solutions to puzzles.
Mega Man 9 was created to offer an experience similar to the earliest of Mega Man games in looks and difficulty. The graphics look as though they belong on the NES as well as the gameplay as this game is tough as nails. There are some modern offerings such as DLC and a ranking system for the worlds players.
This game is hard, very much so that it will take a seasoned player to do well right off the bat. For some this may be too frustrating having to repeat levels over and over again until the memorize them in order to advance without dying.
The original game had no support for dual analog sticks luckily ML2 offers dual analog support for good controls in a 3D environment. There is also four preset options in the settings to adjust how the game controls allowing the games to suit anyone's playstyle.
Interaction with NPCs is key to this game much like an RPG, if one wants to advance in the game they will need to talk to those in town and find out what they have to say.