The law is designed to protect against cyberstalking specifically by punishing harassment online. The EFF came out against it when it was proposed in late 2015, citing all the speech that could inadvertently fall into its crosshairs. Most of the hypothetical examples are mean and morally grey, but not specifically illegal: Repeatedly posting anonymous Yelp reviews to embarrass a restaurant owner into improving their business, for example, is crappy human behavior but Constitutionally-protected free speech.
In a current case regarding the overreaching law, Rynearson v. Ferguson, the EFF and Washington branch of the ACLU have submitted an amicus brief (PDF). It requests the judge presiding over the case issue a preliminary injunction to block authorities from enforcing the legislation, which both rights groups see as unconstitutionally restrictive.
The EFF has kept a close eye on the state's legislation, which has proposed several laws over the years that the group opposed on digital rights grounds. That's not necessarily a flaw of the state, which typically leads the US in proposing legislation addressing new technologies. From being one of the first states to ban texting while driving in 2007 to requiring cops to get warrants for stingray-based cell phone surveillance to ending Counter-Strike gambling, Washington is usually at the forefront of digital rights. But being on the frontier means being the first to navigate the balance between protecting people and protecting rights.