I really like this plugin and would have a few suggestions and I actually wouldn't mind to pay for a "premium" version to get development "faster" or just in general.
How about adding and option, so everyone can vote (even people without an account), this would be really useful in special situations. Ofc would need to kinda track who votes in terms of IPs etc, but still, I think this could be useful and a lot of feedback board have this feature.
Maybe adding "Tags" like "In Consideration", "Accepted", "Working on", "Done/Implemented" and "Declined" (Guess custom strings/values would be the best) instead of just "Mark as Complete".
Those tags should be also visible on the Forum Post later on somewhere (if enabled)
(I use this plugin also as a "Bug report" board, it makes it easy to track.
Allowing "negative" votes, so bad ideas that are not needed can be voted down and even rated negatively.
Making the "Discussion Topic" more visible or better said a "Button" (also in the Topic post later on aka vise versa)
Adding a "Category" option like forums, so people can post within it and It's just there for "order"/containing sub categories.
There is still a text missing here:
Those buttons are for some reason really white (maybe theme problem and not from your plugin but its only them)
Kind Regards