I can't tell you how I found Hetalia but it was worth finding. Axis Powers was pretty good and World Series continues the trend of history overshadowed by comedy between the Axis and Allies and everybody inbetween. If you liked the former, there's more of the same stuff to make you enjoy this one. Never liked it? Scram. Never watched it? Start with either one. The plot boils down to snippits of history, historical events and whatnot portrayed with cuteness, cats and bishounen. Loads of bishounen.
But that's for latter sections. The story is whatever it wishes to focus on. Either being shipwrecked, the formation of an alliance, trading, travelling; zooming here and there in history while teaching you stuff is it's forte. And in four and a half minute segments (Taking out the EP, otherwise it's nearer to five minutes), it's a nice bite-sized snack of history. I've learned a few things but I wouldn't remember most. What I would remember is how crazy it can get. It's in moderation and not a flat out mindscrew or WTF bafflement but considering the stuff it's parodying, it's enjoyable in an offbeat way.
And I should mention that Chibitalia makes a return, with lesser parts than before, Spain and Mini-Romano and Catalia here and there. It's just that oddball. What's more crazy is how it can still infuse history into it. It doesn't make sense and yet it does. Have to give it props for this.
You have to admit, they are good looking. The characters are all about looking good and pulling off exaggerated facial expressions if the situation calls for it. Also about the charm of good looking guys and a girl here and there. It's not incredibly detailed but that's to be expected. The shine and simplicity of the characters work in it's favor and it's a delight to behold.
The OP that lasts a few seconds brings back memories of Axis Powers and I'm glad that it wasn't changed. It's short but grand and it doesn't fit the overall picture but I love it everytime I hear it. The EP is not exactly a shade of it's former self nor is it a completely different person. Neither is it a twin but it retains some of the traits and bits of the one before it. Been a while since I've heard the Axis Powers EP but unlike the OP, it suits it perfectly; silly, whimsical and to add the bow to the present, sung but Italy. The voice overs I enjoyed and especially the title cards for segments, particularly United States of Hetalia! 2! So over-the-top that it's hilarious.
The characters are countries and since we learn about histories about said countries (Parts of at least), it's character backstory. Sort of. But it helps in showing us who they are and those traits represent their actual countries as a whole most of the time. They have their quirks and traits with the main cast being the mains in the Axis and Allies. But some segments and episodes are devoted to others, with Spain and Romano (Southern Italy?) and Hungary and Prussia. You remember whose who for the most part and they're fun to watch.
For a series that's five minutes per episode, you don't expect much but it's more than the sum of it's parts. It's meant to be taken in bite-sized segments and shouldn't be rushed. I learned that after the first series and took my time for this one, which lead to me enjoying it more. Hetalia: World Series is all about charm and wackiness in it's comedy while being a parody of history.