What happens if you release it and it turns out that nobody likes it? I'd have preferred to spend a month releasing a lower-quality app, and then spent 11 months improving it (while people use it and I learn more about what they want) rather than take a year releasing a high-quality app nobody wants to use.
This assumes you aren't just building it for fun, though, in which case building it is the point, and you don't even need to release it afterwards.
