I've found it incredibly beneficial. It has strengthened me. But it has also massively improved my 'mind's eye' attention to my body as it moves into and out of positions, or holds a posture. That gives a kind of body knowledge that can help you to work out what you need to do for your own body to make it comfortable and at ease in daily life.
And of course the mental benefits are good. I can't do pure mindfulness, just can't get anywhere with it. But mindful movement I can manage. By attending to your body you can damp down all the endless preocupations that tend to fill your head the rest of the time.
And, as others have said, it is very non judgemental. It isn't about achieving certain shapes. Its about attending compassionately to your own body while you move, so that you can do what is right for you, rather than manage to copy what someone else in the class is doing.
As for frequency, there would be nothing wrong with going every day, but it might be too strong a target. Once or twice a week brings great benefits and is more sustainable.
Having said that, though, during the first lockdown I did manage to get into a routine of doing the same 12-minute routine at home most days, and that was very good for me I think. Just don't bash yourself with targets.