Review of Shakugan no Shana: Season I

(Impressions on Season 2 & 3 included - Spoiler-free) Take my review as a friend suggestion: Don't start Shakugan no Shana if brought here by its fame. I'm not an hater, I actually loved many parts of the show (season 2 and 3 included), but it's not what I hoped it would be. Episode 1 is almost perfect, the prelude to a magnificent world building and interesting plot development, but sadly nothing happens for over 40 episodes. The first 2 seasons left me with the impressions of a simple love comedy, while the battles had little to no effect in developing the story. In fact at the moment you startseason 3 you have almost no information about the world, the main characters and the "power of existence", and feel in the gut that the first 2 seasons were useless.
Later on many things will return, but mostly as "quiet life experiences".

Main character (Yuji) apart, all characters are pretty good and you grow attached to them, they all have the right screen time to build up a decent personality.
The design and animations are a bit old (time is cruel), but still really enjoyable.

To sum my impression in one word: Forgettable.
Shakugan no Shana isn't an anime I'll remember with love, there is no scene, song or character that left a sign and the plot is pretty weak.

The Novel seems to be a better, but can't be taken in account when rewieving the anime.

I'd love to know how it gained its fame.