Let me start by saying that I have only begun to scratch the surface of the GT-1B so my comments will primarily reflect such. I have used this pedal to explore a wide range of sounds that, with the 99 presets alone will have you bouncing around in all sorts of directions musically for countless hours (one year later and I am still in the exploratory phase). I am using it in conjunction with my first bass purchase, a Fender PJ Precision Deluxe Special. From 60s P to 70s R&B to Blues to Reggae, to a host of Synth and distortion sounds and even an Organ replication, this thing can do it all. And with a simple connection to a computer you can access the very user-friendly software and expand or dial-in whatever sound you choose. Not to mention, once you begin the process of creating your own tones (which has a somewhat uphill learning curve) you'll spend months and months and more on your journey to find the sounds that feel most at home to your style(s) of music.
But what makes this pedal so cool are its amazing features. I plug my PC, mobile (for music play-through) and headphones into this thing and can play basically anytime, anywhere (due to the battery option). I would highly recommend you spend the extra few bucks and purchase the Boss AC adapter to avoid any noise distortion from an after-market plug and to not waste money on batteries when playing at home or near an outlet. You can of course also run this pedal to your amp and either play audio out or through your headphones to take your sound pleasure to the next level.
In short, this is a terrific product for home and practice use and several of the settings (but certainly not all) can also be used for professional use. Also, the built-in tuner although criticized by some as jumpy, actually will dial you in perfectly, particularly when working on lining up intonation and octave tuning. This pedal is also rock solid sturdy and again very portable.
If versatility, great sound production and the ability to have fun anytime, anywhere is your thing, then this is the pedal for you. Last thing, you won't find a better place in Europe to purchase your music stuff than Thomann. Service, packaging and shipping are always top flight.
Get this pedal. You will not be disappointed.