In my new game I'm in mid-classic and so far I have mixed, but slightly positive feelings about the building recosting project. I play snail and I have a rule-of-thumb that a building must have at least a 1% return-on-investment (ROI) to be worth building, unless it provides a special resource I don't already have. For this rule-of-thumb I count hammers, money and beakers as equivalent.
With the new building costs, at snail speed, many buildings that used to be worth it fall below this threshold and are not really worth building anymore in my opinion. But as it takes more time to build the buildings that are still worth it, I hardly notice skipping them.
Less production from buildings means that production from population becomes more important relatively, so having a high population (with its effects on crime, education, health etc) becomes more important.
There are a large number of buildings that weren't worth building before, and are even less worth building now. For example here are a large number of fruit, vegetable and mushroom buildings in the game. Great flavour but they are too expensive for their benefits. Perhaps the cost/benefit ratio of these buildings should be increased by a lot, making them much more worth building and making cities different from each other. One way would be to meddle with health. For example, you could let every pop cause 2 unhealth in stead of 1. And give the various fruits, vegetable and mushroom buildings an additional health bonus. Perhaps not right from the beginning, but around the time humanity gave up on the hunter-gatherer diet and started farming his food. The hunter-gatherer diet was fresh and diverse, the farmer's diet usually wasn't. In fact, archeologist have found that hunter-gatherers were in considerable better health than the earliest farmers. Letting every pop cause 2 unhealth starting with Agriculture tech would simulate that, and give health-producing buildings additional worth. The various fruit, vegetable and mushroom buildings should give additional health (perhaps even 2 health), and the various herd farms (buildable after you place a herd in the city) should give additional health too (they currently don't).
Same thing for other rare buildings. For example, I can build an Onyx mine for 584 hammers. It gives one unhealth and 2 money (actual 3.06). So the ROI for my rule-of-thumb would be 3.06/584 = 0.52% . Which makes it not worth building, and the unhealth is extra reason not to. The Onyx mine also gives Gems but you only need 1 Gems to supply your entire civ. As these special mines only show up in cities that already have one of the 7 map gem types, additional Gem are only worth it if you can trade them to other civs.
Same for e.g. Marble Quarry. It cost 584 hammers and give +1 hammer, +1 unhealth and 2 money (actual +1 hammer and +3.06). So its ROI would be 4.06/584 = a disappointing 0.7%. And it gives unhealth too. In other words, not really worth building.
In my opinion, such specialty buildings like Onyx mine and Marble Quarry should give much better ROI.
By making specialty-buildings more valuable than regular buildings, you make a step towards making cities more unique based on their location.