I have actually used the silly split-screen multitasking thing to have a Safari window on one side, and another app in the other. It's adequate? Barely. I don't think I could really do serious work that way.
But, having the split-screen setup; I have actually gotten some stuff done. It's not ideal, but it's something.
It's something, but it's not enough. A stylus/Apple Pencil makes it almost usable for things that require a finer degree of precision than my big fat finger can provide, but let's say I'm trying to write some code and needed to look something up. Or several somethings. I can split that screen, sure, but what if I'm researching things across multiple windows. Each time I have to switch and dick around with tabs with my fingers, I'm losing time and more importantly, losing focus.
I'd be thrilled if they ever figured out how to make the iPad usable for a full-time dev, but I'm not holding my breath.