I've been playing guitar for about 19 years or so and I remember that my first pedal was a Zoom 505 II, that I got in 2005, haven't owned a Zoom pedal ever since and I am very happy to own this one now.
Right off the bat, after using it, it strikes me as a jack of all trades pedal to have on your pedalboard, it could work on its own for bedroom practice, but I feel that when you incorporate it into your pedalboard is where it really shines...also it helped downsize my board, it replaced my tuner and my phaser.
I am quite fond of the interface, it's easy to use and intuitive, you can stack and edit multiple effects with very little effort.
Soundwise it's good, it's not exceptional, but it's good, it's got something for everyone. There are a few ones in there that sound fantastic, and a few ones that I wouldn't touch with a bargepole.
It's fun, it's easy to use, and it mopped the floor with some other, more expensive multifx units that I've owned.