Great potential used to make a cruel torture device.
The first level of Battletoads is an arcade-style beat-em'-up. It seems like the ideal genre for a game about toads that beat the **** out of things, but the combat turns out to be comprised entirely of button mashing.
There is no distinction between a short but fast, slow but long, short but powerful, weak but long, weak but fast, or slow but powerful attack. There is one attack button that you press repeatedly to defeat your enemies. Neither you nor your enemies have any way of breaking a combo. In the way of defense, there is no block button, and fleeing is highly ineffective.
When fighting one enemy, the only way to lose is to stop attacking or attack in the wrong direction. You don't even have to approach an enemy with proper timing, since they will walk into your rapid attack. When fighting two or more however, there is no way to come out unscathed. Since you can only hit one foe at a time, the ones that you are not hitting will be free to attack you, and you just have to hope that your health bar is larger than theirs. Fleeing does not work either, since the screen refuses to move until all enemies have been dealt with.
The first level is also riddled with instant-death cliffs despite not being a platformer, flying enemies with instant-kill attacks, and enemies that seem to be programmed to spawn at the exact moment you come in range of their attacks.
Upon reaching the second level, Battletoads switches to being a 2D flying game similar to most scrolling shooters. This level uses completely different mechanics, including a new control scheme, forcing you to discard any skills you may have developed in the first level. Because of the flying system, this level actually has some relatively significant player involvement, but it is still mostly a button masher. There are also obstacle courses in this level, which are nearly impossible due to the amount of inertia in the flying physics.
The third level begins in the same beat-em'-up style as the first, but switches to an obstacle course early on.
The amount of trial-and-error in Battletoads is perfectly illustrated between the fighting when the Space Invaders fly to the top of the screen and literally steal the representative blocks from your health bar. There is only one rigid sequence of moving, jumping, and attacking that will dispatch them all and restore your stolen health, and that sequence becomes impossible to execute if you continue moving forward for even a second before realizing what's happening and what you must do to prevent it.
The obstacle course itself has countless problems, including generally ridiculous difficulty, floating obstacles intentionally made to trick you into jumping into them, too much distance between checkpoints, a glitch that forces you into the pit of death without even making a mistake, and a climax so difficult that the game may as well only have three levels.
I guarantee you will not complete this level without a Game Genie or savestates. The game resets after you incur 11 deaths (and you WILL use up several before reaching this point), which is not nearly enough attempts to teach your muscles to navigate a course that accelerates to and from the point where incoming objects become vague blurs.
Battletoads is a complete button masher, riddled with trial-and-error and general unfairness. Stay away and save yourself the frustration.