The only people I have ever talked to who watched all of FMWS and did not get a huge emotional impact are people who knew the spoilers or read the manga first. Don't get me wrong, the manga was good, but I've found that a person's view of the series is permanently altered, depending on whether they read the manga first or watched the anime first.

The problem is that spoilers that shock you in the anime are mentioned early in the manga, with little impact. This does not affect the manga, as the plot in the manga follows a different direction, but it destroys the impact of the anime. This is terrible because the anime, in my opinion, is the best of its kind.

I would agree with you that the series was a bit longer then it should have been, but the "cute and shiny" aspect of the anime fades as the series progresses, and without it we would never develop the attachment to the main characters that makes the series so good.

Full Moon wo Sagashite is a great anime. The anime is powerful, moving, and has great music. I tried to read the manga afterward, but found it lacking.

The differences between the manga and anime are frustrating. I think this is a series where you like the one you see first, because both stories are emotional and leave a lasting impression. When you switch to the other (manga/anime), you find a different story and don't like it as much.

Both the anime and the manga have great stories but they are significantly different from each other. That said, I think if you have a choice, you should watch the anime first. I love the music.