It's interesting how so many people seem to just assume that newer tools are needed for more efficiency/productivity. Assuming the same code needs to be produced, the important part is the knowledge required to produce that code and have it be efficient and of high quality. The tools have absolutely nothing to do with that aspect of the job other than to provide a level of comfort to the developer. That's a highly personal thing and necessarily prohibits any usefulness of a "my tool is better than yours" argument.
I greatly prefer emacs over a fancy GUI IDE for the largely same reason that I would prefer to do documentation in LaTeX over Word or LibreOffice. When the tool is largely invisible (which becomes true with enough experience), I can completely focus on the *content* that I am creating. That doesn't mean that I think my way is the best way for everyone, just the best way for me. It's where my experience has taken me. Not that I haven't tried newer tools or been forced to use them from time to time, but there's a high bar for them to get over to truly improve my productivity.
My only real problem with GUI IDEs is when using them precludes not using them. While I've managed to mostly avoid the MS world throughout my career, where it has impacted me has generally been painful. The tools there tend to assume that everyone uses the same environment and make little or no accommodation for other environments. Yes, I know this is not universally true, but true enough that I will continue to avoid that world as much as possible. I can use emacs, make, and gdb on Windows, OSX, Linux, and more. Can the same be said about Visual Studio? (Running Windows in a VM is NOT a valid argument.) The rise of Linux as a common base OS in the embedded space is making this easier every day, thankfully. I'm not really trying to bash MS here, it's just a particularly easy example.