is in any way the new one better than the old one?
More pointedly: does it justify its price premium over a NOS vintage one?

If I have to stick to a simple, plain, one-word answer then mine is: no.

Now I don't want to be seen as one of those 'only-vintage' types that scorn anything modern, and I admit I think that TH have done a terrific job in getting this out and the buzz can only do good, spread the Heuer passion and ignite a nice number of new fans like the re-issue of the Monaco and Carrera did.
Still as I ponder on the topic, and admitting the square-cased Silverstone, like the Monaco, is too 'cool' for me:

1. It lacks the 12-hour recorder that for me is essential in any chrono (same fault, as it were, of any Cal.15)
2. It does have the continuous seconds, whereas one of the feature I like most in the old Cal.12's was its very lack, which gave a very 'neat' appearance to the dial.
3. Last but not least, on the contrary probably foremost for many: the suggested retail price is at a higher level than a NOS vintage one with all the additional perks of box and papers.

Now, I myself started with a Heuer Carrera 1964 re-edition and so I love re-editions, still there was a very major point in those:

- Original Carreras of the type are as rare as hen's teeth, and almost impossible to find in nice conditions, let it alone NOS
- Though by no means cheap in absolute terms, the price was roughly the half of the vintage one.

So in the end, apart from the very personal question of liking or not the style, the re-issue had a specific, value-for-money appeal that IMO the new Silverstone lacks.
Just my 2C...
Have a nice w/e everybody.
Cheers.
Fabrizio