Yes, ninja tabi shoes are comfortable. They are made with 100% cotton with reinforced stitching and toe and sole support to keep the foot comfortable while allowing it to move.
They aren't too uncomfortable, but remember that they're like thong sandals that cover your entire foot. You'll want tabi socks to keep your feet from getting too sweaty and stinky.
I've not worn them but have met those who have and they always feel like dancing around when they wear them so Im assuming they enjoy Ninja Tabi shoes for comfort and balance a light shoe.