I wondered why this extension does not have a Live Demo... and it's because this is a "Do-it-Yourself" Joomla gallery, so there is no standard configuration!
Admiror Gallery uses Joomla's own Articles, Categories, Image Folder and Menu to create a Gallery. Which sounds as if it might be complicated or tedious to work with, but it's not! I set up my whole custom Gallery in an hour, including the learning curve and looking around the Admiror website.
I'm very happy with my custom gallery. I was able to create just what I needed for an educational/resource website. For me, it was easiest to select a Joomla Category List for a menu: this made an instant Gallery with links to all my Gallery pages.
Thumbs are generated automatically from the images folders (you can adjust size and shape of the thumbs in the plugin settings.) I put my folders within the images/sampledata/ folder and my images were all detected automatically.
This is a brilliant plugin. (And remember, it's a plugin so it needs to be enabled in the plugins area of the Admin.) There are plenty of settings so you can tweak it to look just the way you want.
The best way to SEE what this Admiror Gallery can do is to play with it. I'm not a programmer, but I'm a fairly experienced Joomla user so I didn't have much trouble setting it up. If you're a Joomla Noob then you possibly need a Gallery that has everything arranged for you. But if you know how to work with Categories, Articles, and Menus this is basic stuff for most Joomla users.
I was wondering why Joomla doesn't come with a core Image Gallery. If it did, THIS is the way it should work. Admiror Gallery is not an overly-simplistic gallery however. It's very flexible.
Like I said, these programmers are brilliant, IMO. This is a wonderful plugin for Joomla.