The ruling said the privacy interests cannot be limited to what the IP address can reveal on its own "without consideration of what it can reveal in combination with other available information, particularly from third-party websites."
It went on to say that because an IP address unlocks a user's identity, it comes with a reasonable expectation of privacy and is therefore protected by the Charter.
Personally I agree with the majority opinion here. "For the safety of children and crime victims" is too often used as an excuse to unleash wide-reaching attacks on privacy.
Police will still be able to obtain the information they need when the cases involving children and victims of crime happen, they just need to get permission from the courts. This ruling seems to prevent law enforcement from doing an internet analogue of "carding", requesting and obtaining random Canadian IPs in search of something to prosecute.