One of the things I like the most about 5E are the online tools and apps at DNDBeyond.com. Very useful and getting better all the time. I like that it’s a RAW implementation of the character rules and can be used to make sure you’ve got all your modifiers right. They recently added full access to sources for the player app, and I use the app as my character sheet when playing.
One thing I don’t like is that after buying the books I have to turn around and buy them again on D&D Beyond if I want access to those rules. (And even again on Roll20 if I want access there, but that’s a different post.) However, they frequently run good sales and they’ve currently got a 25% off all books deal running. I’m adding a few. It includes the upcoming Ravenloft book, too, though I’m holding off on that for now. Sale runs through May 2nd.