I have been using this Adobe Digital Edition 4.5 for a while, and I think it's basically safe to say this is the crappiest software in 2018.
The software crushes basically every 2 mins (I am using Macbook Pro 2017) and becomes almost impossible to scroll down the pages. I used "almost" because sometime it gives you false hope of moving down 2 centimetres in 10 seconds and you secretly pray that this is not crushing again. When it crushes I have to force quit and reopen, and of course you have to memorize the page you were reading because obviously this thing is not keeping your history before it crushed.
I have been fine putting up with this software because, well it's free. But it's significant hurting my reading experience and I couldn't even finish a book of 200 pages in 3 months. It's so painful that I am willing to register an account on Adobe and spend 10 mins writing this just to tell you how much this software sucks.
The only reason I am using this software is because the book I am reading can only be opened with this tool. But honestly, I would be astonished if even one person is in Adobe is even developing & supporting this software.