I pretty much echo the general consensus. Despite the quirky gameplay that was the result of it originally being a different game unrelated to SMB, SMB2 USA was the better game. It was fun, imaginative, and introduced things now canon to the SMB series. Meanwhile, The Lost Levels was just a "mission pack sequel," utilizing the same core graphical assets (with some additional background tiles), music, and gameplay as the original and cranking up the difficulty far beyond what anyone would deem reasonable. It did nothing to move the series forward, and it just plain wasn't fun.