The effects are great! However, these feel like old-old terminals, as in terminals from 80s after decades of use. Good quality phosphor monitors are a lot crisper than the screenshots.
Can confirm. Source: the gently used VT420 on my desk that is hooked up to a RPi for retro-vibe goodness. Text is crisp and clear, no "smearing" like in the screenshots.
(Can also confirm that heavily used terminals definitely show degradation.)
VT420 must have had a good crt design. They'd run 18 hours a day as catalog terminals in university libraries with no problems. I'm sure most made 5 years with only minor brightness or contrast loss. Good solution with minimal service required--just cleaning any debris from the keyboard. Basically plug and play to the serial multiplexer.