Suspiria is a well made horror movie, not boring, building slowly the tension and with a great director work behind it.
If you expect a classic horror movie "american style" you will be disappointed, but if you are looking for an adult horror movie then this one is for you.
Everyone talking about the last 20 minutes.... well, last 20 minuts must be considered and evaluated in the totality of the work of Guadagnino, as his own personal touch.
Above all, i suggest to watch it without prejudices and with a clean mind, to enjoy the atmosphere, the uncomfortable situations, the evil sensation that Guadagnino can offer us.