I think the most important thing to remember when dealing with Reactive Forms is that you need to “react" to changes properly. If you’re not careful, you can run into problems where the form changes, then you change the form, and so on until it causes a big loop that slows things down.

I also think the reactive forms API has some confusing bits. Like “touched” vs “pristine" vs “dirty”. These can be difficult to differentiate if you’re not familiar with them.