i dig my gt-6b. i especially like the octave (by itself or paired with touch wah and/or fuzz). plus the looper is a lot of fun.
it's nice having pedals to change the effects. the interface is a bit daunting, but that's because you can make it do pretty much anything once you learn enough.
more importantly though, the gt-6b is a great way to learn about effects. i no longer use mine, but that's because i know what i like, and i've started buying individual pedals that do those sounds better than any multi-effect could ever do them. this point will apply to any multi-effect, including any pod (which i've never actually played)
"master your instrument, master the music, and then forget all that &%$# and just play" charlie parker