Oh the humanity! Get a grip people! You all act like it's the end of the world or something. I personally have never used preview for anything related to PDFs. I grew up with Adobe Acrobat Reader and Pro and the first thing I do with a new Mac is set all my PDFs to open with Acrobat Pro using the get info command. If you think this is bad buy a cheap Windows laptop and get FoxIt for Windows PDFs and get ready for pure hell! Preview has always been like the Stickies app for me since I rarely use it and the interface is probably the worst thing since Windows 2.0. Although it could be and should be better, I never lost any sleep thinking that Apple was going down the tubes because of the Preview App! Haaaa! Their customer satisfaction rating isn't near the top for nothing. But Whiners will whine and babies will cry. Meanwhile, I will be working in the new and improved, or much improved, Final Cut Pro 10.3.1. I also Use Adobe Creative Cloud Apps which have lots of bugs in their new versions as well, but nothing major that affected workflow or getting the job done. I suggest if you wanna hear about real problems talk to my Windows 10 buddies! Peace Out!
Preview is just the tip of the iceberg. Real problem is the new PDFKit which is used by many third party software. I have no idea why Apple thought it would be ready for release when it contains serious bugs that in the worst case leads to data loss. Released OS should not contain these kind of bugs in any circumstances.
This reminds me of Yosemite with discovered bugs which were only fixed after 8 months after Yosemite was released, it remains to be seen how long it will take for Apple to fix PDFKit.