I disagree.
The degree of usefulness for the Great Works is often situational and the benefits can be quite good if you plan a bit ahead. However, I tend to go for the culture bonuses, not the trade routes and military experience. For example, in my current game I have built several Great Works throughout the ages, all giving bonuses to theatre, since theatres are quite cheap and quick to build. I also have dyes as well and the theatre has become a very useful building for expanding the boarders of my new cities and growing them.
I try to build works that offer bonuses to buildings that I plan to build in nearly every city. The +6 for the Great Work and the +1 for the bonus may not seem like much at the time, but it adds quite a bit of culture throughout your empire. This is especially true if you have built several Great Works in a city then build a national wonder that offers a culture % bonus. IMO, I believe it is much better to build Great Works sooner to receive the long-term benefits, rather than save your artists for later periods because even after that art period is discontinued your buildings still receive the culture boosts from your Great Works.
This is much more realistic to how actual culture is created slowly over time and was a great change. Plus the Great Works that were included were chosen wonderfully and the RI team managed to cleverly add each art period into the game to top of it all. Imho, this has to be one of the best additions that has been added to date.
I disagree too. (but also agree it is a great addtion, just need to be attuned)
First of all, as proven by the guru of culture games (called Jesusin), through his over hundred culture games on various conditions (his article is coined a must read to be a good culturemonger), culture bombs avered to be almost best for fast culture wins. Of course, culture victory isn't necessary the purpose for getting more culture in such city or that one, but it is often proven that immediate gains are best. Just like slavery proved without any doubt (with perhaps very few exceptions) that whipping is better than building organically through mines in vanilla BTS.
Second gripe of why I think culture works as they are now, that is weak in weigh, consists of three points:
1) Normal settings on RI makes more civs per maps. On standard for vanilla BTS, it was 6 AI's while RI puts 8 AIs (or 9 don't recall exactly). That means smaller empires, thus the empire-wide bonus is weak until one reaches a critical mass and at that point, why not just win. Yes, we can custom the games to any number of AI's, but considering we are talking about standard RI games, that is the situation.
2) Settling the GArtists are better worth than getting the Great Work. IIRC, a settled GArtist is worth +12

and 3

. That's undeniably stronger for culture fights and add that a nice economy bonus (the gold). Yes, I suspect Culture Works will double after 1000 years and that makes almost even, we are talking about only early ones. Once reaching 500AD, that's it, the settled GArtists are better. And perhaps, I'm too generous at the date. And a GArtist never obsoletes when settled compared to the empire-wide feature of Great Works.
3)Honestly, occasionally, the bulbing techs are better in worth than getting that small culture bonus. It not only push the player in better place in the tech race (and if tech trading enabled, maybe, give some trade chip), but the worth is like 3000 beakers. Much better than the weak culture bonus from Great Works that takes time to build up. Again, it's the now that is important, not the potential later effects.
I'm not up against "historicity" arguments because it's somewhat bogus. A simple example of two choices where the first gives doubtless better outputs will end up with the first choice being chosen. Great Works' values are too weak compared to other choices for now. The implementation is indeed really interesting, but if given choices, the player will be attracted to the one that gives best. Unless it's pure role-playing...but since you play EMP, I suspect you like challenge.
Another example of historicity gives tuning to features: mounted units are weakened because RI is supposed to show that charging hordes of mounted units conquering empires makes no sense, hence the -25%

. What would happen if that malus never happened: the player will at some point realize it's pointless to go on with slow infrantry wars when mounted units are swift and the choice is gonna be chosen by itself unless the player wants at all cost shoots in its foot. It's basically the same situation with Great Works: I see stronger choices as it is now.
As for another example straight from another play who has done a misplay: he wanted to play a Genghis game where the goal is roleplaying the mongol invasions asap. He has chosen Animal Husbandry first (btw, for vanilla bts), but his only food resource he had (to start an empire, we always have to start with food!) was a wheat resource. Nonetheless, he finished his worker, but that one has nothing to do because of the Agri delay. Let's assume he loses later and whines about that. Well, if he puts aside the historicity argument for going straight Animal Husbandry and gone for building his empire first to give him a chance to win, then he would have performed better.
Historicity arguments to its extreme leads you should always lose as american natives once reaching 1500s. Is that fun? No.