I personally wouldn't, but its up to you.
There will be no external differences bar the front and rear lights. The interior will be different, I don't think its gonna be a vast improvement over the current one, the seats for instance will remain the same, my understanding is that its only going to be the centre console. Not sure what effect, if any, the facelift will have on resale values of the ST, were you looking to buy something like a Finesse it might be a different story.
There's another thread on here about it.