It works well for me, but I have a personal preference for command line tools. I use emacs as my editor and am able to do everything I need on my Linux server (this is strictly for personal/hobby programming). There are a couple good source code aware (but not project aware) text editors for the iPad that work well with Working Copy, a really nice git client for iPad. On occasions when the Linux server was not enough, I set up Github Actions to respond to commits made through the use of Working Copy + an editor (Textastic in my case, though I'm not ecstatic about it, it does get the job done).

I'd prefer a real IDE on a few occasions (work is C# and Java). Trying to do some side projects to relearn or expand my knowledge of them and their libraries was infeasible on the iPad alone.

In the end, my conclusion is that if you don't need an IDE and can use a CLI or git-based workflow, then the iPad is a fine tool for programming and writing in general. I'm not even stymied by the relatively small screen, it's still better than the monitors I grew up with. The fullscreen and split screen modes also work well with my particular manner of maintaining focus on tasks (I use fullscreen/split screen on my MBP almost exclusively as well).