The premise of Ah! My Goddess is quite original; Keiichi, a bit of a loser with terrible bad luck, is using the phone one night when he accidentally gets through to the 'Goddess Hotline' which sends him a goddess who says she'll grant one wish.
Rather than money or power, Keiichi's wish is that a goddess like her would stay with him forever; this leads to a romantic comedy which is, in my opinion at least, very well-executed.
Belldandy (the goddess) and Keiichi end up living together in a temple which is given to them to look after whilst its owner goes off on his travels to attempt to attain more enlightenment. The anime basically follows the relationship of the pair as it develops (very slowly) and the problems they sometimes face, mainly due to Keiichi's horrendous bad luck.
It flows quite well, and the later introduction of Belldandy's sisters Urd and Skuld helps a lot with the comedy aspect of the series. Over time the relationship between Belldandy and Keiichi grows and develops despite the attempts of friends and relatives to get in the way. I ended up caring quite a lot about whether things would work out for them, and unlike most series of this genre AMG managed to grip me through both series.
One thing I can say about AMG is that it manages to use ecchi (which I normally find annoying and pointless) in a way that increases the comedy and actually fits in with the context/story.
The backgrounds were generally quite badly drawn, but I don't personally pay much attention to those anyway. The characters, on the other hand, were all beautifully coloured and animated. I love the designs of Urd and Belldandy, and the art matched up to the story and characters perfectly.
The voice-overs were fairly average - nothing you wouldn't find elsewhere - but I've generally come to expect that, what with there being so many animes out there. They did suit the characters for the most part (I watched it Subbed) and I would definitely watch other animes with the same voice actors in. The few episodes I did watch dubbed were horrific and I advise you never to go there. Please. For your own sake. I have to take a full point off for the dubs, they really were that bad - especially Belldandy.
As a whole, the music was good and in keeping with the themes and moods of the anime.
Although some of the characters were fairly generic, it worked. Belldandy and Keiichi remind me very strongly of Chii and Hideki of Chobits, which is another really good anime rom-com. I would recommend watching Chobits if you do like AMG.
Belldandy herself is a good character in the sense that she's very innocent and well-meaning. One thing I didn't like about her was her complete subservience to Keiichi, but this was mostly counter-acted by Keiichi being very humble; he never orders her around or anything like that so it doesn't seem like servitude as much as wanting to please him because she loves him. Besides, I'm fairly sure my dislike for it is purely to do with cultural differences.
Urd is probably my favourite character - she's always trying to 'seduce' Keiichi but her ulterior motive is to get him to man up and confess his feelings to Belldandy - something he really does need a kick up the backside with. Plus, as I said earlier she manages to bring ecchi into the anime which is actually funny.
Skuld is your typical whiny little sister; doesn't want big sister to be taken away from her, makes herself into a class A nuisance in an attempt to prevent it. She's very annoying.
Marrler was the worst one for me. I won't say what it is because that would be a spoiler (I think), but her weakness is just downright stupid. She's a pathetic excuse for a demon and I honestly think the series would have been better if they'd changed her into a more formidable enemy (I know it's a light-hearted series but there is a limit...).
Keiichi... well, he's nothing new. Unlucky with women, money and everything else. Clueless when it comes to romance. Essentially good-hearted. Bit of a cookie-cutter character but it wouldn't really work if he was any other way.
The only other character I can think of worth mentioning is Sayoko. She's a complete bitch and just wants Keiichi so she can spite Belldandy, since she feels threatened by her. She can't stand the idea of another girl getting attention from the guys at university, so she tries her best to humiliate Belldandy and steal Keiichi from her. I wanted to strangle her all the way through.
AMG is a harem involving goddesses, which incorporates a lot of situational comedy and focuses on the relationship between Keiichi, a human, and one of the goddesses, Belldandy. It's a good anime to watch if you like rom-coms and even as someone who isn't usually into that kind of thing I would highly recommend it.
*Chobits (many similarities in relationship dynamics)
*Ouran High School Host Club (vaguely similar humour)