I just got back from Yosemite. I went in at Happy Isles on May 5th, and came out half a day early due to a serious case of sunburn late on the 8th. (I'd brought winter gear, foolishly forgetting sun protection. Paying for it now with blisters.)
Yosemite Valley
Backpackers campground across from North Pines is open; I was apparently the first visitor on my way in, but there were already four sites taken a few days later on my way out. I met some guys on the trail on my way out that hadn't been told about it, though. They'd been told they needed to head up the trail at 5pm; possibly not all of the staff at the wilderness office are aware? I dropped by to give them details of these conditions on my way out, and one mentioned quite a few had just showed up recently.

Beware: they no longer accept cash! The pipe receptacle that took envelopes had its top removed on my way out, even though the instructions still talk about that pipe. You have to download the , and scan a QR code on the bulletin board. The cost per person is still $8, and doesn’t impose any additional fee.

The app isn’t too big, so I was able to download without trouble while in the valley. (Degnan’s is the only spot I found that had useful free wifi, fwiw. And some nice beer astonishingly cheap.) There is still an alternative way, but it requires getting to some kiosk in Curry Village before 5pm. Also true of Camp 4, which is $10 per person. Already getting full of climbers.
For a few years I've been telling folks the that fine for leaving food out was up to $3500; I'm pleased to see that, no, it's up to $5000!

Valley to LYV (6200 ft)
Mist Trail is beautiful and trouble free.The Merced is flowing mightily.

On the north side, the JMT has a few spots where snowfall still covers the corners of switchbacks, but that’s unlikely to be much of a challenge except for those unsure of their footing.
The portion of the JMT beyond Clark Point which is closed in winter currently has hikers walking through several waterfalls and and 6-inch ice water puddles. Fun, but a serious soaking for the unprepared.
LYV has many new blowdowns, creating new chaos, both the valley and the campground.
LYV up to Half Dome junction
The trail is a creek in many sections.
A *lot* of blowdowns. Near the top there’s one big spot with so many it is better to leave the trail for a hundred yards or more. Not something to try at night.
???? 
My first night was on the ; it's still a great spot. It was completely dry the afternoon I arrived, but I got a few inches of snow overnight. This view looks SW down towards LYV.

JMT to Forsyth Trail
Snow varies from 90–100%, so very few signs of a visible trail. Dead reckoning on snow is often better than trying to follow the summer trail anyway.
The first below is looking down at Sunrise Creek just beyond the SW Clouds Rest turnoff, the second is a quarter mile later, looking up.
??? 
Firm consolidated base, with shallow postholing to maybe 6 inches, but slippery on sunny afternoons.
The bad news re Sunrise Creek: flowing wide and strong enough that fording would require caution. The good news is that there are many new blowdowns for crossing, unsurprisingly.
Forsyth Trail to Clouds Rest
(Thus perhaps useful on the JMT to ~10,000 ft)
100% snow. This is looking back south .

Dead reckoning is even better, since the snowpack is probably covering so many small blowdowns that would usually get in the way. With trail crampons, this was the most enjoyable part. But be sure to bring high-SPF sunscreen.
Here's my below the NE end of Clouds Rest. But first, a tree.
???? 
Oh — Clouds Rest was impassable. The loose snow on top of the firm base was deeper and soft, so even with crampons on I was slipping around quite a bit on the slope. This is the first good view peering over Tenaya Canyon down at Mount Watkins. Clouds Rest was living up to its name, embedded in blowing icy mist.

This is the last photo I took that came out. The ridgeline here is about sixteen, maybe twenty feet wide. Further along I could sometimes see through the mist that the very top of the NE end was even narrower and taller, with the SW end occasionally looming even taller beyond that. I'm pretty sure what I saw was a 12-plus foot cornice stacked on top of that already sphincter-tightening arête. (I've always called it the Dragon's Back — but I can't find any indication that it has any specific name, except maybe "the spine".) I'm not suicidal.
I
My goal was to use CR as a shortcut back west, so I went down and considered the bypass instead. But there was no trail visible, just a 40–50° slope of soft, soft snow. Even with snowshoes and a pair of ice axes, I'm pretty sure I'd eventually slide further down than make forward progress, so I took the easy way out and just retraced my steps. Anyway, by this point I'd realized my sunburn was serious enough that I was going to be in pain (with eyes partially swollen shut) and needed to get out of the back country.
But, honestly, it was still awesome. One last photo, looking back toward Tuolumne Meadwos , approaching CR.

--
Richard Wood