Things are highlighted as you go through, the buffers showing various values in scope is updated all the time, you can add certain variables/objects to be watched. GUD (built in) supports pretty much anything GDB can do (and also supports JDB afaik and a some others), check the manual for full feature set https://www.gnu.org/software/emacs/manual/html_node/emacs/De.... DAP (plugin/extension) is a bit more flashy and "modern", I haven't used it too much though, but it looks interesting https://emacs-lsp.github.io/dap-mode/page/features/. A nice video showcasing some of it can be seen here: https://www.youtube.com/watch?v=0bilcQVSlbM.
