There's not a lot of point in it, really. It's a light-hearted time-waster, but it feels as if they didn't really have a plan for the show beyond its title. "Kaijuu Girls! Great, let's make it!" Anime's turned everything else into girls (e.g. battleships, guns, electrical appliances), so why not daft giant rubber monsters from the Ultraman superhero mega-franchise? (Do a Google image search for all the kaijuu that these girls represent. I swear you'll boggle.)
It's not serious, but it's not a comedy. Maybe it has parody elements, but I wouldn't know since I don't know Ultraman that well. It's just girls being a bit silly and occasionally turning into kaijuu (i.e. giant monsters). In this show, those are basically superhero costumes. Everyone's a member of GIRLS, which is a training and/or certification school. The show's storyline is... mostly absent. Not a lot happens. Kaijuu sometimes go on rampages and destroy stuff, although that's liable to be because they got emotionally stressed after hearing spoilers for an anime movie.
This show has no episodes I'd call "good". It's not aiming that high. It's mostly pottering along on a time-filling combination of Cute Girl Conversations and Let's Turn Into A Kaijuu, although that said I was mildly diverted by ep.10 ("throw people off a temple"). As for the characters, they're likeable but thin. (Well, it is a four-minute format.) The three regulars are based on the Ultraman Capsule Monsters:
Aki Miyashita (Agira
) - orange hair, stoic, no discernable personality. Her focus episode is ep.3, in which she finally manages to transform because a car had been going to crash into a kindergarten!
Miku Ushimaru (Miclas
) - always hyper and energetic. Also a big fan of other Kaijuu Girls, in particular Red King.
Reika Shiragane (Windam
) - pink-haired, serene girl who's secretly a raving otaku. She first transformed into her kaijuu form when emotionally moved by boys' love manga.
Theoretically the girls' outfits could be called revealing, especially Eleking's, but that's meaningless since the show's art is chibi style. (It becomes more realistic for the girls' transformation sequences, but they don't show naughty bits.)
It's okay, but it's the kind of thing that at best you'll delete after watching and never think about again. It's mildly amusing, but nothing in it is even half as funny as googling what these kaijuu really looked like. (The real Miclas
looks retarded, while the real Pigmon made me laugh out loud.) Apparently there's a prequel novel series that's darker and more serious, though.