You can't make a direct classification against Gamecube because it's better at some things and worse at others. Kind of like N64 vs. DS.
I would say close to GC but has a hand reaching towards Wii.
And from what I've read about this chip, it's not as powerful as the TEV units in the GC & Wii but is more flexible and has many more modern shader effects hardwired into the chip. What does that mean? It means 3rd parties already know how to work this chip and won't have issues with learning the ins&outs of it like the odd ball TEV unit that you have to learn to use only for that system. That's why most 3rd parties never bothered to push the system since there where no other applications for learning the TEV unit.
To make it even easier, it's like being in a group of friends where everyone speaks English a little different (some with an accent, some with lots of slang) but you can basically understand what everyone saying except for one friend who only speaks Russian. Now a few of the other friends know a little bit of Russian, but only enough to communicate.
That Russian friend is the TEV unit, everyone else, including the 3DS, speaks English.