It changes and gets softer over time. Less cringe and depression, and more quirkiness and friendship, but with a little dysfunction and sarcasm thrown in.
It really changes around the "school trip" arc and comes into its own around then. To be honest, it changes so much after that arc, first gradually and then more quickly, that I would even go as far as to say that the latter part of the manga is a totally different experience than the beginning.
If the Anime had started right before the school trip arc and summarized the beginning of the series, I think it might still be ongoing. This manga gets better as it goes to the point where I feel like the intro part could actually be rewritten to be more like the middle and the end and it would be a net positive.