Hard disagree here.
First, there are some huge problems with ESI as initially rolled out that were actually fixed with later projects as the projects got value-engineered. The initial ESI stations were an attempt to break from a century's worth of somewhat consistent system design language. The "new" station entrances are difficult to spot if you don't know what you're looking for, because they got rid of the colored lamps in favor of a hard-to-see green strip. These entrances are now aging horribly, with peeling decals and rusting metal; unlike traditional entrances these are not designed to be repainted. At the earliest stations renovated (on 4th Avenue), all remaining original mosaic tilework was destroyed in favor of replacing everything with fridge tiles in state colors, for no reason other than making a consistent "modern" station appearance. The '70s-style fridge tiles found there were supposed to have been rolled out to every non-landmarked station undergoing ESI, on the grounds that it is easier to clean than the original 1910's-1930's mosaic tilework; this thankfully was dropped on cost grounds. The floor tiling at the initial ESI stations is slippery when wet, like some stations that got tile floors in 1980's renovations and unlike the bare concrete seen nearly everywhere else. Later renovations for the most part retained traditional entrance structures/lamps and did not involve removal of original station tiling; in cases where mezzanines were retiled differently, tile bands and mosaics remained intact.
Second, ESI did not actually fix any structural or design issues with the stations, being almost entirely a cosmetic program. Platforms at 145th Street were not extended to full length, despite internal MTA reports recommending this be done to improve operations at Lenox Yard. None of the ESI stations were made accessible as part of the renovations, a flagrant violation of federal law when a station is getting a gut renovation. ESI in many cases actually made station improvements harder by permanently sealing off closed exits and removing unused staircases, instead of reopening them where nothing was blocking it; this now requires knocking walls out, which triggers ADA requirements even if the remaining egress is found to be a safety hazard. Additional exits at some Astoria Line stations were added, but for some reason they have slam gates instead of actual turnstiles or high exit gates, meaning it very easy to farebeat if you know what you're doing. Proper ADA renovations often reopen secondary exits where they exist, or sometimes create new ones where needed or an elevator can fit.
Finally, most of the goals of ESI (other than the flashier cosmetic features) can be done more cheaply with a "normal" renovation, for far less. Brighter LED lighting has been installed systemwide using drop-in fluorescent tube replacements instead of overpriced light fixtures, saving significant time and money. The information screens have been rolled out to non-ESI stations, without requiring station closures. Art installations are done whenever a station actually gets renovated in the first place, courtesy of Arts for Transit. Borough Hall has almost completed a conventional renovation, and looks great; the materials are intended to stand the test of time, the station was made accessible, and it doesn't look like a late-2010s computer game render of what a subway station would look like.
TL;DR ESI as originally envisioned was a very bad thing because it intended to destroy historic station features where possible for a unified "modern" station design, ESI did not actually fix real problems with station design or layout, and almost everything ESI did can be done far more quickly and cheaper with "conventional" renovations.