I agree, I'm generally sceptical of new AI "features" in the browser and will be turning most of them off. But the translation feature (which has been in Firefox for a while now) is great. The difference is that translation in a browser is something that is clearly useful and has always been AI-based to an extent, so shipping with a local model for translation is a strict improvement (leaving aside any difference in translation quality, which I have not noticed). The other AI features are not obviously useful IMO.