Mighty-O is basically just a bare-bones coffee shop whose main selling point is vegan donuts, though their selection is limited and they tend to sell out of stuff very early. I went there with my friend around 10:30 a.m. one day, and they'd already sold out of their cream-filled donuts and more exotic varieties.
That said, I enjoyed all the flavors I tried, particularly the "french toast" donut and the strawberry glaze.
Their tea selection is limited to mainstream bagged varieties, which was a let-down (why not loose-leaf?). Also, dairy milk jugs are prominently displayed in the cooler behind the cash register, which was a bit of a turn-off.
In the end, if you get there early, Mighty-O will probably have some fresh vegan donuts. If you go later in the day, you'll be stuck with whatever is left.