It's a best-selling anime based on a mega-hit browser game, in which WW2 battleships are cute girls. Also it's retelling Pacific naval battles of WW2 so that the Allies are evil zombie abominations and victory goes to the adorable, innocent Japan.

I thought it was okay, with my favourite bit being the accidental swearing in the theme song.

Let's discuss moe anthropomorphism. There's a lot of it about. I'm not talking about the computer-girls of Chobits, because that's just SF and there's nothing weird about that. Japan likes turning improbable things into cute girls, e.g. racial slurs (Hinomoto Oniko), jihad terrorists (ISIS-chan), diseases (Ebola-chan), etc. Some anime examples are:

I'm boggling about the charcoal. Anyway, KanColle has battleship girls. A bunch of schoolgirls wear tank parts on their backs and limbs, then put on jet ski boots and zoom across the waves. They're cute. They're lovable. They have comedy slice-of-life episodes like the curry competition. They have out-and-proud lesbian relationships. (Someone of them might have sought boyfriends had there been any male battleships, but there aren't.)

That's one of the show's personalities. If you like cute girls doing cute things, watch KanColle! (It's not a fanservice show, though. There are no panty shots and even the clothing damage in battle is family-friendly.) However also...

2. The show's also dealing with war. Named characters can die traumatically, although the impact of this is reduced by the "Marked For Death" war movie cliches before they go off to battle. The show's more than ready to punish main characters hard for getting a rush of blood to the head and charging off solo to be heroic. Fubuki is useless in ep.1 and puts herself through hell in order to improve enough to be useful. The show intermittently takes itself more seriously than you'd expect, which makes for some reasonably decent drama.

3. It's recreating WW2, but with tweaks. The Allies are undead horrors who launched an unprovoked attack on the world, whereas Japan's ship girls are fighting purely in self-defence! Hurrah! Japanese war crimes? The eventual machine-gunning of civilians after capturing Wake Island (ep.3)? Those things never happened! Don't be fooled by details like the Kongou girls being half-English, because the real Kongou-class battlecruiser was indeed built for the Imperial Japanese Navy by Vickers in England, just before WW1. This show is a close enough recreation of military history that even its own characters in the last two episodes start talking about "repeating history" and being "bound by fate". (Apparently at least one surviving Japanese war veteran was surprised to learn that the ship he'd served on was being used in this anime.)

Historical accuracy explains some things that might look unintuitive to the fanboy. The Yamato is an all-conquering super-ship, but this is seen as making her too expensive to risk in battle (as well as being inconveniently resource-hungry).

4. It's adapting the browser game of the same name. That explains the never-seen Admiral, for instance, who in the game is the player. (The English subtitles make him male, but all Japanese references are gender-neutral.) Those instant-repair buckets are also from the game, although the anime had to restrict their availability for drama and hence make their characters look like idiots to anyone who was used to the game mechanics. (In WW2, of course, the Imperial Japanese Navy's supply lines did indeed get stretched thin. It's a conflict of game logic vs. history.)

Personally, I'm not that up-to-date with all the history and so I don't really care about the revisionism. You'd need to be a pretty hardcore viewer to think "Abyssals = U.S. Navy". It's hard to get too offended about a battle against zombies directing swirly death monsters that look like a cross between Tex Avery cartoon sharks and an H.P. Lovecraft nightmare. The nearest it comes to being dodgy is its implication (for drama) that Japan was massively outgunned, whereas in fact it was Japan who had a numerical advantage at Medway. Then there's ep.12's subtle implication that a fallen character had been reborn as the undead, which is tragic and cool but poses thematic problems if you're dead-set on the WW2 revisionism reading.

The show's Engrish is wildly entertaining. Nao Touyama plays Kongou and mostly manages to sound English rather than American, which she didn't in Kiniro Mosaic. That doesn't matter, though. The main attraction is the theme song, which is an all-time great. Anime fans will be revering it for decades to come. Admittedly even a native English speaker might have trouble trying to sing "weigh anchor" without sounding rude, but the injury was self-inflicted. No one was forcing the songwriter to mix Japanese and English like that, or the singer to scream out the relevant words. "The morning light is so bright... WAAANKER!!!"

The show's quite good, I think. It's a reasonably decent war movie, with added cute girl comedy and a late sprinkling of "screw fate". Military war buffs and game fans apparently have issues with it, e.g. the anime's choice of which to use of the game's 160-odd characters. Personally I'm not bothered. However I also wouldn't call the show a runaway brilliant favourite or anything. "Quite good" sums it up, I think.