I think it's a cool idea, kinda like LikeALittle but for organizational stuff.
To pre-select the group of people who can participate, you might want to look at a model like Yammer, which validates accounts based on the email domain. This way, you wouldn't have to invite specific emails (which would make me less trustful of the anonymity). If you go on Glassdoor, you see a lot of this dynamic where employees will write reviews meant more for the company than for perspective hires. It's because a lot of companies don't have a really good feedback system where the anonymity can be trusted. Might be a good use case to focus on in the beginning.
To pre-select the group of people who can participate, you might want to look at a model like Yammer, which validates accounts based on the email domain. This way, you wouldn't have to invite specific emails (which would make me less trustful of the anonymity). If you go on Glassdoor, you see a lot of this dynamic where employees will write reviews meant more for the company than for perspective hires. It's because a lot of companies don't have a really good feedback system where the anonymity can be trusted. Might be a good use case to focus on in the beginning.