Taste on aesthetics I can agree with: Some will love the looks of one over the other, but that's the same situation with anything. I don't think there's much argument that both are good looking cars (whether the new 'Stang is better than the old one is a different question altogether), and I don't think there's any argument over whether the the Mustang appears to offer better value than the 370.
Where the Ford could fall over is the interior quality, something Nissan massively improved on with the 370, and certainly I've yet to be impressed by any of Ford's connectivity options in their vehicles (my Ranger is particularly horrific, and it's only a year old!). In terms of styling, again that's down to the individual, but I think it certainly has the same dash of flair that the 370 has.
No, I look at it purely from the basic viewpoint of wanting a fun GT cruiser with a big engine and RWD, whilst giving me something more exotic than a four-pot but with some good shove, and I want all that on a budget. In that respect, I think the 370 to Mustang comparison is a very fair fair one, and I think it's very heavily weighed in the favour of the Yank. At that price point, I would expect it to nab a few sales from Audi and Porsche as well.
I think we're all forgetting just how big a deal this car is. It's the first ever Mustang to be offered here in RHD, and they're giving us the V8 option too in full-fat glory. This is a legend, an icon of motoring, and it could take off over here just as much as it has in the US.