1. Don't join if you're just going to pay the membership fee and say you're a member. Like the poster said above, PBK is really the only society worth mentioning.
2. If you want to join in order to take part in the chapter's activities and/or try for a leadership position, or if there are other perks to joining, then I'd say go for it as long as the membership fee isn't outrageous. I am definitely not familiar with this honor society, but if your school has an active chapter that you want to get involved in, it would be no different from any other student organization. I joined NSCS for like $75 and got a rather nice scholarship out of it, plus did several service activities with the group. It's still not a very strong addition to the app, and I just lumped it with a few other things in an "Honors and Awards" entry, but it's a bit more substantial than just paying the membership fee and saying you're a member.