It's a good concept, but the infrastructure only exists in the SF bay area and southern CA. From the start, the system has been plagued with shutdowns and lack of hydrogen and the stations. Now hydrogen has skyrocketed and it looks like BEVs and PHEVs are gaining the momentum.
I got a CPO Mirai in 1/2021 for $12K and it came with $15K worth of hydrogen on a debit card. To drive that same distance on gas at 30mpg with regular gas would have cost around $6-7K, though. But I drove 55,000 miles in that car for free, although service every 5,000 miles at Toyota dealers authorized to work on them was a hassle and not cheap for some of the visits. When I got it, hydrogen was $16/kilogram. It drifted down to $13/kilo, then about a year ago went to $20, then $30, then $36 at most stations.
Bottom line, if you live or work near hydrogen, it's a good way to go overall. The new Mirai looks like a Lexus, and has more power and range (which was never great). You could get a $54K new one for net low $20Ks after all the credits PLUS a $15K debit card.
Another thing is the fuel tanks are not recommended to be used after 15 years, so there's a sunset on those cars. This applied to the first generation Mirai, not sure about the second gen.
https://www.motortrend.com/reviews/2021-toyota-mirai-fcev-yearlong-test-review-verdict/