The game does have its frustrating moments, but for the most part, The Lost Levels is a great follow-up to the original.
The gameplay is similar to the original. Make it to the end of the level and touch the flagpole. The first difference you'll instantly see is that the 2-player mode is gone and replaced by character selections. The first is Mario Game and the other, Luigi Game. The difference between the two is that Luigi jumps higher than Mario and has poor traction like he's on ice. So if you want to make an already punishingly difficult game harder, play as Luigi.
Nearly everything from the first game is in the Lost Levels. You got the power-ups, the mushroom, the fire flower, the starman, and the 1-up mushroom. If still the game isn't hard enough, the addition of the poison mushroom will tick you off. Touching it will do the same thing as touching an enemy and you'll end up confusing it with a regular mushroom and die.
The graphics are a little bit updated from the original. The ground is more detailed and doesn't look like blocks, the clouds have eyes, and there's detail with any sudden hazards like the windstorm, which will push you back.
The main downside of the game, is that it's way too freaking hard. Overdoings with the level designs, random windstorms, hammer bros. that CHARGE you, BACKWARDS warp zones, trampolines that send you flying too high, too much use of invisible blocks, I could go on and on. But even if you are a hardcore veteran gamer, such as myself, the extreme difficulty is a pain in the a** and is hard to forgive.
Even with the brutal challenge in this game, The Lost Levels is a good game and the true successor to the superb original. If you suck badly at video games, don't bother with this one. But masters of the original and veteran players should take a look.