To give the Russians their due, I would expect a number of improvements to be present in a truly new tank design, and I imagine it really does have quite a few bells and whistles beyond what they could do with yet another modernized T-72 variant.
As far as the claims of radar signature reduction are concerned, I am somewhat conflicted. I can see how the Russians would be quite concerned about the vulnerability of their armor to air attack. Thus putting effort into making their tanks blend in with ground clutter makes quite a bit of sense and is almost certainly a much lower bar to clear than making a fighter that can hide against a background of sky. That said, the US has only just recently come up with a stealth material system for the F-35 that is truly durable enough for an aircraft that doesn't have to be constantly babied. Yet I doubt even a baked in fiber mat would hold up long to the kind of abuse a tank is expected to endure on a regular basis.