Many issues - generally really don't like the new format because it's much harder to get to simple things like "create a red box", "add text", "edit text", "add signature", etc. But also is critically screwing up my documents in ways that make it untenable to work with. If possible, I would get off of this product (I can't because my employer buys the licenses) and here are the reasons why:
1. Literally reverted my entire document after working on it for 10 days because it couldn't identify some of the text characters (it's got a ton of formulas in it with unique characters). So if I had not been saving every 5 minutes due to crashes, I would have lost the entire document to editing unique characters into ".". This is awful - I can't believe that this product is capable of essentially erasing everything I worked on 10 days into working with special characters.
2. It crashes CONSTANTLY. I am not doing anything that requires a lot of RAM/only simple tasks. Literally just adding text boxes to a simple document and putting red boxes around some of the above mentioned formulas. I'd say I've had a crash at least twice a day. The auto-save feature seems to only save occasionally - on average I probably was losing an hour's worth of work every time it crashed until I started saving every few minutes.
3. Again, why is it so hard to get to simple stuff like draw a box? I go to draw a box and the section where drawing boxes is supposed to be is grayed out. Anyway, editing text and adding text boxes has been a total nightmare. It's totally inconsistent. It will add tabs within text boxes seemingly without reason (I can't find the format options, so I definitely am not choosing to format). For some reason, if a text box has multiple rows sometimes (not always, but about about 50% of the time) it will separate each row into a separate text box so that I can never edit it again without creating a new text box and copying in all of the text from the separate boxes. It sends to back text boxes sometimes and makes it so I can't reach them without undoing my actions and I can't figure out for the life of me how to bring to front (I think I found this option but it doesn't appear to make what I'm editing... come to the front).

I am so fed up with this product. I know other people who's organizations have reverted to other software packages and I'm jealous of them. If this was a product that I used more extensively at work (I do use it frequently at work, just not to the extent I have over the last few weeks), I don't think I could handle it. Also, please just Google "Adobe DC review" and look at the comments in the positive reviews by PCReviews or whatever the first hit is - the review is absolutely not consistent with user feedback. Or Google "Adobe DC terrible" and you'll find literally thousands of articles. What happened to the versions of this product that made sense? It seems like you just keep on adding features for the sake of adding features, not because the user community (not the same group that want to play on their iPhones - we all are working on this program, not noodling around in our spare time) has asked for it. Give me simple drop downs and user interfaces and fix these bugs in the next version. Who in the world is editing their PDFs on a Tablet? if they were, this interface would still be incredibly difficult to use. Let's get back to good, Adobe.