To be more specific: this ruling confirms that tracking users with only implied consent is illegal. What Facebook tried to do here is to make user tracking an integral part of their service by putting it in their TOS. The GDPR is quite clear that such tracking can never be a legitimate business interest and therefore a) users must agree to it explicitly, b) consent for tracking may be withdrawn at any time, and c) withdrawal of consent may not be tied to the rest of the service offering (i.e. a business may not refuse service if users decline to be tracked).