Super Mario Land 2 is a fun, drunken mishap. Much like Super Mario Land, it's an excursion Nintendo tries to pretend didn't really happen--they're both weird games with weird elements that don't really pop up elsewhere in "Mario canon" and I cannot believe I just said "Mario canon." The one blister in this statement, of course, is that Wario exists and continues to exist despite the government's attempts to arrest him for money laundering.
I never played much of SML mostly because it's so archaic, short, and generally ugly. SML2 is more of a complete game and throws a lot of strange shit at the wall to see what sticks. Keep in mind this employed a "do any level and world you want in any order" ethos, which wouldn't get revisted for a very long time, so I guess that means SML2 is revolutionary. You're not going to find bubble blowing hippos and hockey-mask wearing baddies with knives stuck in their heads in any of the new Marios. Even Shyguys--a leftover from Doki Doki Panic--made it out alive from the patchwork crap of SMB2, but characters like Heavy Zed The Helpful Owl are resigned to the purgatory that is SML2. Like you, I too wish for Heavy Zed to make a Smash Bros appearance as an assist trophy someday.
I've never heard the SML2 medley even in Smash Bros as a remix and that's a shame, given how catchy and upbeat it is. The composers did a nice job changing the leitmotif up for the different zones, which I suppose I should talk about now. There are 6 zones, but we all know the best ones were Halloween Town, Mega Mario, and Fucking Space. The last one is particularly interesting because it drops in the previous game's endboss as the world boss, and boy is he an asshole to fight with the low-gravity jumps. Mega Mario Zone always disappointed me slightly for two reasons: you couldn't operate it like a super sentai megazord and fight Bowser in a secret kaiju battle, and the world boss sucked. You'd expect to maybe fight a robot at the end, but instead it's the 3 little fucking pigs. Why these fairytale monsters are in charge of a monolithic tribute to Our Lord, I'll never know.
You get carrots to complement your mushrooms here, which I imagine was a result of the FDA cracking down on Mario possibly ingesting nonstop hallucinogenics. To balance out this drug-induced trip, Nintendo injected a good amount of Carrots into SML2, which grant you floating properties via a pair of rabbit ears. Makes PERFECT sense. On a more negative note, it is sad to see Mario engaging in cultural appropriation, as he now dons an Indian feather for his fire flower power-up. I expected more from you, Mario. You'll be hearing about this in my next hate-spewing series of Tumblr posts and Tweets.
This all culminates in an epic battle to the death with Wario. It's kind of neat that you have to fight a dude who has the same powers as you and even the same items, but is fatter and bigger than you. It's like if two twin brothers engaged in mortal combat, but one of them has a shovel for a hand and the other has a tin plate in his forehead. In the end, I'd recommend SML2 as a "beginners" Mario game over the others. It's not as complex as Mario World or as tough as Mario 3, and the jumping mechanics are as forgiving as they've ever been. It's fun and doesn't wear out its welcome, unlike those fucking hippos. It's on the 3DS virtual console so you're basically a piece of shit if you don't own this in some form. It is the essential oldmario and I won't hear otherwise.