I've just installed the plugin and here is an update.
I installed every component that this author offers, of which there are three (WHMCS Bridge + WHMCS Bridge Pro + WHMCS Bridge Plugin). I used a fresh PageLines installation with the defaults for this test.
The plugin installation went smoothly. There are two things I have found that do not work in the plugin.
1. Client login to WHMCS does not work when the Fix IP option is enabled. The developer responded to my support ticket by telling me to disable the option, which worked, but unfortunately there was no solution provided so that i could use the Fix IP option. This is not critical.
2. The WHMCS Bridge widget "Account Info", which allows a customer to sign in and see there account stats in the sidebar does not work. The developer has not responded to my ticket yet. This is critical.
Regarding aesthetics, I set an option in WHMCS Bridge to inherit the WordPress theme. That did not work well. When I navigate to the WHMCS pages they do not display correctly. Everything is misaligned, icons are missing, etc. I know this can be fixed, but I am a novice and do not know any coding, so I'll need to hire someone for that. If anyone thinks they can help me with this part I would greatly appreciate it. I am very eager to learn.
In conclusion, I would say the functionality is good but it will requires a significant amount of research and work to make it look good.