In some ways, Marshall and Lily were the core of How I Met Your Mother. They were the steady (for the most part) and loving relationship was one that Ted was often pining for. And they served as the complete opposite to Barney, who was mostly concerned with womanizing and living a carefree, family-less, child-less life.
And many people love Marshall. He's very cuddly and goofy, and cuddly/goofy characters are always popular. But some people don't like him for the exact same reasons. Let's delve into exactly why he was so loved... and so annoying.
Overrated: Drama With Lily
In virtually every sitcom ever made, there is an on again, off again romance that provides much of the drama. And in the early days of How I Met Your Mother, that drama belonged to Marshall and Lily. Unfortunately, will-they-won't-they drama is a little banal and cliché. Fortunately, the show largely avoided this pitfall post-season 2, meaning the cliché was largely relegated to its early, burgeoning seasons.
Underrated: He Is Very Successful
Marshall is often the "dopey" one within the friend group, and it's often very easy to make the "dopey" one a bit of a loser. And if not a loser, then at least an underachieving, lazy character with little self-awareness. Luckily, How I Met Your Mother largely avoided that pitfall by actually making Marshall very successful in his schooling and career. It proves that it wasn't blatant stupidity driving his silly behavior, and it adds some welcome depth to his character.
Overrated: The "Goofy One"
Unfortunately, a trope is still a trope, and Marshall falls into the "goofy one" of the primary friend group. It seems like there always has to be a "goofy one," and it's getting kind of old at this point. Most of Marshall's idiosyncrasies come from his belief in myths and supernatural creatures and his bizarre superstitious habits like licking airplanes. Everyone has their quirks, but sometimes Marshall veers a little too much into them.
Underrated: He Never Cheats On Lily
It is very refreshing to actually see a faithful and loving husband on TV.
When it comes to sitcoms, it's usually the husband or boyfriend who is portrayed as promiscuous and unchaste (which usually leads to an argument, which usually leads to the trite on-again-off-again drama). And if they don't outright cheat, they are typically tempted. Not so with Marshall. He remains studiously devoted to Lily throughout the series, and that subversion of sitcom tropes has to be commended.
Overrated: Catchphrases
Let's face it - catchphrases are kind of lame. Unfortunately, How I Met Your Mother often employs them through Barney and Marshall. While Barney is certainly the catchphrase king, Marshall has his own lineup of oft-repeated lines, primarily "lawyered." It can certainly be funny, and we wouldn't blame you for using it in everyday life. But catchphrases have diminishing returns, and after a while they get pretty stale.
Underrated: Feminine Traits
Another refreshing subversion of sitcom tropes is the personality traits between Marshall and Lily. In general, Lily is the stoic, "masculine" one while Marshall is the more emotional, "feminine" one. He's very sensitive, very loving and affectionate, loves Broadway musicals and "girly" drinks, and he even cries when his boss yells at him. Meanwhile, Lily is far more stoic, confrontational, and aggressive. It's nice to see, and it's far more realistic than the typical "tough guy, sensitive girl" pairings we so often get.
Overrated: His Love Of Food
The show often makes a point of Marshall's love for food. He's on the coupons of a local pizza place, he untiringly hunts down the best burger joint in New York City, he can often be seen stuffing his face at the bar on the apartment kitchen.
It's kind of funny, but "loving food" isn't really a personality trait (who doesn't love good food?), and characters gorging themselves isn't nearly as funny as sitcoms suggest.
Underrated: Telepathic Communication With Lily
A neat little character bit between Marshall and Lily is their seeming ability to telepathically communicate. This can best be seen in season 6's False Positive while they're telling their friends about Lily's pregnancy. Of course, they're not actually communicating through telepathy (or are they?). But it's a great way to verbalize the inherent connection that loving couples have and their ability to know exactly what the other is thinking.
Overrated: The "Small Town Guy"
Another trope that Marshall inhabits is that of "the small town guy." Being from St. Cloud, Minnesota, Marshall continuously has trouble fitting in with the chaotic hustle and bustle of New York City. This is specifically brought up in season 4's The Best Burger in New York, which depicts a newly-arrived Marshall as the scared and timid small town guy too scared to walk the streets alone. It's funny to an extent, but not as funny as the show thinks it is.
Underrated: His Rage
Marshall is arguably the nicest member of the core group, and he can be incredibly patient. But he does have a fuse, and when it's lit, Marshall goes absolutely berserk. He's proven to be an adept brawler, and he's laid into the likes of his boss, Ted, and Amanda, and he's even thrown basketballs at children. It's a nice little bit of character development that proves Marshall is more than the carefree, laid back persona he often exhibits.