Still not perfected. Two years ago it was much more difficult, Amazon needed the file in html, separate images and zipped. Now it's possible to upload a doc file (just like BN always took) and it's fine.
I just received an email from a reader saying she couldn't see the images contained in Flash of Light in her reader.
I went to my Kindle Fire and it's fine for me. (Small but fine) She didn't say what reader she has.
I did a magazine trial--impossible to read full page because it was designed for a large physical magazine. To read it in a Fire meant lots of scrolling and moving the page around. Big hassle. Maybe it works on an iPad.
So is it worthwhile to include images? Only if you accept that not all your readers will be able to see them.