Money For Old Rope
It's an improvement on Dune 2, no question. The graphics and sound are much better, and it adds some cutscenes.
It does nothing that Command & Conquer didn't do 3 years earlier - in fact, it's essentially less. Like Dune 2, it only has one ground surface, making for bland looking levels and a lack of gameplay variety, and not many units by modern standards. It's clear that it's been aimed as a cash-in and time-filler, something Westwood would never have done in the old days.
The Bottom Line
Not a sequel to Dune 2, but essentially a remake using the technology at the time. And it was showing it's age. Only buy it if you can get it cheaper than Dune 2, or you don't have a DOS-capable PC. Dune 2 has more charm, and a genuine place in history.
You can't take a 1950s music system, change the casing, add fancy speakers, and expect it to match a current model. This is the same situation.