Hey @pvrtomg,
I know the notification asking for a review can feel intrusive, and even annoying. Sorry for the trouble there.
The review system and allows developers and users in general to have an idea of how a plugin is doing and is useful information for those looking for a new plugin for their site. Also it is a sign of quality as those stars are awarded by users and are a reflection of their experience with NextGEN Gallery.
The notification should be dismissible, otherwise the WordPress Dashboard would end up clogged with tenths of these notifications from all different plugins you use.
If you or someone on your team are not able to dismiss our notifications on a website, I suggest you to open a new thread in the support forum so we can proceed with the troubleshooting.
Thanks for your feedback.