Okay, I leave it to the better German speakers to deal with the German side. 'What gives?' and 'What's the deal?' aren't rude, but they are informal.
I was just trying to address the point that 'Was ist los?', as I understand it, is more a neutral question wanting information, wanting to know what's happening, like 'What's up?,' 'What's going on?', 'What's the matter?'
In contrast, to me at least, 'What gives?' and 'What's the deal?' both assume that something is happening or has happened, and that the speaker already knows what it is, but wants to know why it's happening, why someone is doing it. It's not necessarily angry, but it could be a little annoyed, impatient, or suspicious. I thought 'Was soll das?' was actually pretty close, but I realize I don't always have a firm grasp on the nuances of conversation, so if you have a better idea, I'm eager to hear it.
The thing is just that to me, translating 'What gives?' as 'What's up?' isn't really right; that's just a case where dictionaries have to define it somehow, so they use something similar, but it's not really an exact synonym. So I'm not (yet) convinced that 'Was ist los?' is really right either.
Part of the problem, though, may just be that I'm not sure we really say 'What gives?' much any more, at least in AE; it's an expression that reminds me of slang in books, maybe old murder mysteries. 'What's the deal' is much more current, at least to my ears.
I have a vague memory of another sense of 'What gives?' that's more like 'So? What did you find out (when you went to ask)?' But to me, it's still asking for explanatory background information on something people already know some information about, not asking for initial information.
If that makes any sense.