It was pretty impressive: the sound was well balanced/equalized, ⅓ of the concert was done on acoustic guitars, and since the theme of their tour is "In our room - an evening with In Flames", they had a couch, a low table, some plants and old-school lamps on stage (my phone is too old to take pretty pictures, sorry). They invited several people to enjoy the concert from the couch, on stage, casually emptying some beers, … Some songs were played on violins and cellos by guests, they even sung several tracks that they liked but weren't theirs. During the whole concert, a friend of their was painting something neat (the Jester Head devouring the moon) to be sold in favour of charity.
I started to listen to this band when I was 12 years old (Trigger was quite a shock ♥) with their album Reroute to Remain, and every time they release a new one, it's not more of the same, but something different, in a new direction, but still with a distinctive In Flames taste. I warmly recommends to listen to their albums, in reverse release order if metal isn't your favourite music genre.
In summary, I was expecting a regular metal concert, but it felt way more like an exposé of the band's universe, and it was quite refreshing to listen to some songs from a new (acoustic) angle.