I (tried to) use DnD Beyond literally yesterday for another DM's game. He wants to use DNDB (against my preferences). I couldn't even create a fighter. I gave up. Will have to create my character by hand and input everything manually in their awful character sheet. And if you're doing that, you might as well just use a form-fillable PDF character sheet.
I can't find a single thing it does that I prefer to Roll20 (which I'll grant you isn't perfect). Roll20 has a stable enough voice chat, automated rolling, facilitates online play (which is the only play I am doing now or in the foreseeable future).
Even in an in-person game, I could run the entire adventure using Roll20. DNDB would be a nightmare to navigate. You have to back out every time you want to look at a character or monster or read the PDF.
Sorry if I seem so negative about this, but I know there are better tech solutions. The wide adoption of DNDB just means that we're not going to get it. Even the 4E stuff 10 years ago was better.