The story is your basic magical girlfriend plot line; if you've seen this kind of show, you know what to expect story-wise. It doesn't really do anything new in this department. Each episode tends to be a different misadventure of your main cast, and some of them can get kind of ridiculous, stupid, or boring. Mamotte Shugogetten tends to put more emphasis on the comedy than on the romance, though the humor can be really hit and miss. It might be enough to get a little laugh out of you, or might not.
The show has a cast of about 8 main characters. A lot of the time the show seems to just cram every character it's got into each episode and it can feel kind of overwhelming and unnecessary. The characters themselves are, again, not anything very new, but I think they can be enjoyable. Shaorin and Tasuke are your main couple, and they're cute enough, just your average couple you would see in this genre. The rest of the cast is the center of comedy, with the main gag being that they're all constantly trying to win the affection of either Tasuke or Shaorin (with the exception of two of them). This joke can get really stale when it gets used so often.
I think the art style is very nice, and Shaorin especially has a great design. Another one of the characters, Ruuan, also has a unique design that really sticks out. The animation itself isn't always great, but it does what it needs to do for this kind of show. The voice acting is fine and voices suit the characters. The background music is just generic synth/MIDI-sounding stuff, nothing special there. However, the opening -- and I hate to say this -- is really the best thing in Mamotte Shugogetten. I didn't skip it even once. Its a really awesome song with visuals that suit it perfectly. The ending song is also pretty nice, with interesting and creative visuals.
So, I didn't hate Mamotte Shugogetten, but I was let down. I was expecting something more unique and interesting. I guess the best way to describe this show is "harmless" or "mediocre". It doesn't really bring anything different or new, but it also isn't atrocious or offensively bad, and there is some charm to it. If you go into this show expecting a serious show and something really fresh and new, you're going to be seriously disappointed. But if you just want some simple lighthearted fun, I guess this is an okay anime for that, but you could do better.
The manga is pretty different and focuses more on the romance instead of the comedy, and it also doesn't have the filler that the anime does. So if any of the ideas in this anime interest you, I'd recommend to just read the manga instead. You will have a much better time.
