I tried this plugin to link Wordpress with Invision Community (IPS). According to the docs at Invision, there are 2 ways to do this. I chose the first one linking IPS to WP as the server as opposed to IPS acting as the server. My review is based on this experience but I'll try the other way too.
It quick and easy to set up, and clearly there's a large amount of work gone into it, but once I'd got the connection configured, that's when I found that the logins expire after just 600 seconds, that's just 10 minutes!
According to the support section, it says this is fixed at 3600 seconds, unless you upgrade to the pro. But 10 mins isn't an hour, which would be okay at minimum for a WP site member to browse and compose a comment or review on Gallery images, post in a forum etc in Invision Community forming part of the same site.
Secondly, probably 90%+ of this plugin is locked down and almost everything seems to say you need to upgrade to pro. Instead of 7 tabs full of settings and options you can't use, why not create a simpler lite version with a non-intrusive ad for the pro version benefits?
If you want a simple Single Sign On OAUTH solution to link your WP user accounts to your IPS accounts and sync basic profile info for the convenience of your visitors but then forget about it, it will do the job but as crippled as it is, this probably isn't what you are looking for, unless you want the pro support and anything beyond the bare minimum.