I assume everyone already knows TFT is live at Kickstarter, but...
Regarding adding value, the "new" part has to be the physical things. It's hard to imagine you're getting your money's worth for the new rules.
In the "Where We're Going" section of December/November 1978 The Space Gamer v.14, Howard Thompson wrote about TFT:
An open-ended system like TFT is too big to be made perfect on the first pass with the resources available to any wargame firm. It was decided to develop TFT as an evolving system rather than design it with constraints that would let us iron everything out from scratch. We aren't perfect and aren't designing TFT as if all our current ideas are perfect and final answer. [...] That's saying up front that TFT will never leave the development stage. [...] There will always be playtesting [...]
40 years later, it's still not going to be perfect (no matter how much $ goes into the KS). It would be cool if we got updates to the PDFs (like software) for the next X years, however.