It's slow, bugged as hell and the result is subpar compared to a real native app... At least it was like that when I tried it (again) 3/5 years ago
My SO just finished a term project that used Xamarin.Forms. Conceptually the framework is perfect then you actually use it and want to off yourself. MAUI, if taken seriously and isn't only a rebrand, could be quite an accomplishment and a great tool.
I'm not sure about the state of Xamarin Forms these days, but back when I worked with it a few years ago even the sample apps had memory leaks on iOS. I agree that conceptually it was amazing, as was Xamarin itself. If Forms doesn't have leaks these days it would definitely be a great way to build cross-platform apps.