These strings are one of the only options out there for 8-string guitars with a longer than 27" scale length, and are very good value economically.
They do last fairly long, but tend to sound 'dead' after about a month of fairly infrequent abuse, although GHS fast fret really does wonders to keep them 'alive'. If you like to always have 'fresh' strings, you'll likely need to change sets every two weeks or so, but you should do that anyway, right?
One of the pros/cons of this set is that these strings sound bright and have a large, albeit somewhat 'tinny' resonance on the treble side.
Nice crisp initial response when using aggressive pick attack, palm mutes on the bass side sound tight and focused, and clean tones ring out nicely with subdued natural harmonics still flavoring the sound.
They are great for clean playing as well as metal riffing/djenting (there's a reason the boys from Meshuggah have used this brand for ages).