This is my personal experience and thoughts
Gold flow - Really in an ok spot. It could be a little better (I mean by a very small amount.) The only issue isn't gold flow, but rather itemization.
Experience - Underleveling is still an issue, but far better than it used to be. If you are still hugging an ally champion while they are clearing, you can catch up. The jungle monster experience scaling better with lower levels is also a huge boon.
Utility scaling - So far in a good spot. They have plenty of build choices (I tend to go AP bruiser on some supports and max CDR on almost every one.) There is one issue I'll mention in items, though.
Actives - Goes along with Utility scaling. All supports provide a variety of different utility, sometimes even better than an item. I'd say it's up to personal preference and what your champion does (I build Locket of the Iron Solari on almost every support, AP or otherwise, but almost never on an aggressive mage support, since they get better "utility" from building AP.)
Solo laners - This comes down to each individual champion. The problem with supports going solo lane is when they become overbearing such as when Lulu was going top often. More recently, Leona and Alistar are seeing play as junglers, and considering how absurdly good their ganks are, definitely need toned down (personally think Leona's ult cast range should be reduced.)
Identity - Similar to solo laners. Sona's identity is the Aura support and she does that well, even after the rework. Can't really say anything about Zilean.
Item(ization) - The "required" Sight Stone is the biggest issue in regards to support itemization. 800g is a lot of gold early on, especially if you and your carry are unable to get kills in lane. Not to mention with the lack of choice in SS (150HP isn't useful to all supports) and the recent buffs to trinkets, Yellow Trinket is almost always better than Sighstone. This is a bigger issue in SoloQ, but can still be an issue in teams.
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Costs 800g, gives you 4 wards upon purchase and then refreshes upon returning to base, takes up an item slot, and can be bought anytime. Frees up trinket slot for "more vision." Very little incentive to upgrade to Ruby at all since it's just 800 gold for 250 HP and one more ward.
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Costs 250g, gives a ward every 60 seconds up to 2 at a time and refreshes while roaming, takes up the trinket slot, and can be bought past level 9. Frees up an item slot for more utility.
The price is just no contest: 550 gold isn't worth a item slot or 150 HP that you may not use well: If I get caught out as Zyra or another squishy support, 150 HP is not going to help me much. If I need wards early game, yellow trinket still works well. Ward amount, it's not difficult to have 3 wards up with yellow trinket. Also in my experience, I see supports often roaming for well over 5 minutes: eventually you'll have to back to get more wards, which could put you at a disadvantage if done poorly. Yellow trinket, just keep roaming and it will come back. Item/trinket slot-wise, item will almost always be better, especially late game, and more often than not someone or two will have a red trinket anyways. Levels depends on a per game basis, but if you are falling behind, that yellow trinket can still easily help with vision, and you can simply just play passively/farm under turret bot lane. And finally, the 3 ward limit spreads the responsibility to other team members as well and again considering how good Yellow trinket upgrade is (especially for the cost) there is little reason not to buy it if you have 250g to spare. If your team isn't happy with your only 3 wards, they are more than free to buy more wards (and if they choose not to, that's on them.) That is personally a lot better than what it used to be (Support had to spend tons of gold on wards and be near useless if caught out.) and I definitely do not think they should nerf change trinkets, just that people should learn how good they are and build it more often. I make a habit to upgrade yellow trinket as almost any other role when I have 250g to spare past lv 9, not just on support. It helps out a ton and sometimes I ever have more wards out than the support. And it only cost me 250g.
TL;DR Trinkets are by far the best thing to ever happen to supports. Help your support: upgrade your trinket (especially if you are sticking with Yellow.)