The frustrating part is that no one will note the benefits of the work - they'll just find something else to complain about.
That actually depends. They are selling this as a "rip the bandaid" type of thing. That should mean the payoff should be something noticeable. We should see less slow zones, service disruptions from power outages, service disruptions from trash fires, and service disruptions from signal issues. We've already been living a constant drip of weekend and evening shutdowns. Hopefully this should pay back with having less of that too.
If "Rip the bandaid" really means ripping the bandaid, then it should like Government Center. 2 Years of pain for a now pretty cleaning looking station versus 3 years (probably more) of constant construction that makes a new normal.
I'm worried this becomes like that Orange Line signal upgrades. Somehow I see that excuse so many times, yet even after years of it, it is still the same issue. And pretty sure it just got worse (though a lot are the trains - maybe)