What do you like best?
The performance of the photoviewing. Even though its a browser based tool, showing images is near native speed, as long as you have a good connection to the server its hosted on.
Furthermore I like that the interface has a dark tone, this is both great for not burning your eyes out, as well as bringing attention to the images, which is most likely what you want.
Its also extremely simple to install, and has very few dependencies, none of which can't be installed through the ordinary package repos.
What do you dislike?
The sharability. Currently this application is a strictly single-user tool, with some options to share photos, but no options for guest accounts.
Also there is no support at all for videos, which I can agree is maybe not required for a professional photographer, but for hobby photographers it would be nice to support video too. Fortunately I'm a programmer so I've implemented this feature.
Recommendations to others considering the product
Keep an eye on the issues on github, Tobias has mentioned there is a roadmap, but there is nothing in print, which means that he can change it anytime he feels like it.