In my experience people will find time to give you feedback if you give a quite specific framework.
- Did you find the sign-up process intuitive?
- Was it easy to find the information that required about x?
- Did you find the colour scheme appealing?
A broad ‘please review my app’ tends to make people think whoa, I’m way to busy with my own work to spend an hour reviewing someone else’s.
Could you ask a few specific questions that people can focus on and answer?
I don’t mean to appear patronising, so apologies if that is how I’m coming across. My goal here is to help you to get some meaningful responses (and to guide others in the future).