Many people look back on Hetalia as a sort of cringe-worthy period of anime fan history, and with good reason. However, this isn't something that should stop you from watching the series (unless you wish to pursue the very open, extreme love for the anime that many people had back in the day, which I don't recommend - not from personal experience, but it does give off a lot of second-hand embarrassment) especially if, like me, you are a fan of culture and history.
First of all, you must understand that Hetalia is based on a webcomic of shorts making light of historical events and cultural stereotypes that happened to get fairly popular in Japan - that being said, they are disjointed comedy skits pertaining no particular storyline besides clipped segments based on things about the world that the author thought was funny or interesting, with each episode including several different segments and only spanning roughly 5 minutes. Oh, except for the romantic subplot most predominantly present in the first season of the anime between two countries as children; something I personally disliked.
Regardless, the humor is silly and immature (which explains the premature fanbase, of course), with several sexual jokes thrown in; nothing sophisticated like Sayonara Zetsubou Sensei's remarks about the state of Japan, but I believe that the context of what it is separates the show from most. It's very much an adult anime shrouded in child entertainment.
It cleverly incorporates elaborate jokes about world history, which is the entire reason I decided to rewatch it. For example, in the early fraction of WWI, the French army had to change their outfits because the bright blue and red was easily spotted by the enemy - this is represented in-anime by frequent references to France's 'flashy' and useless outfit in the WWI segments. It's not truly chuckle-worthy humor, but the subtle historical allusion to small insignificant things like this made me grin and guided my interest through the entire series. All 6 seasons, even if the first season is fairly dry. Another thing that piqued my interest was the intriguing ways the country proxy-characters are portrayed. The mangaka incorporates both modern-day stereotypes and the history of that specific country into their development; like Russia's loneliness and ghastly personality having been caused by the hardships Russia has faced all throughout its existence. It honestly makes me happier than it should, but also means that if you're one that dislikes stereotypes and can't handle fun-poking at your or another nation's expense, then this series is obviously not for you.
And last but not least, I have to praise the fantastic dub. The horrendous over-exaggeration of the accents of each country make the show worth watching in itself solemnly because it may be the only series that it would ever ACTUALLY work with. If they didn't have the accents it would be much, much less entertaining. It may just be the best dub that Funimation has ever done.
I suppose, all-in-all, if you're a world-history fanatic, some sort of linguistics major, somebody who wants to see what the world is like from the eyes of a Japanese guy that writes comics about things he likes in his free time or someone who has it in their heart to laugh at silly, basic humor, there's no harm in giving this anime a go - and I recommend waiting for the later fraction of the second season to give it up, skipping ahead a few seasons if you're not a fan at first, or even just reading the webcomic instead (a much better-suited format than an anime, for this one, I think). The composition and a lot of the characters' actions in the first season or two were particularly boring to me, but I gradually found it more interesting as I watched more. Also, I genuinely wish the episodes were longer - loading a new page for every 5-minute episode is a pain.
