Is Nikon D800E a good camera for landscapes, portraits and still lifes?

I have Nikon D7000 and this camera is wonderful.
But I would like more quality, more plastic and more harmonious colors.
So, I would like to buy Nikon D800E.

Yes, the D800 and D800E are both excellent landscape cameras. They are also replacing some of the Hasselblad camera that product photographers have been leasing.

I suggest you add the D800E to your current system and keep the D7000 when you need the extra reach of an ASP-C sensored camera

Why would you change cameras
to get "more harmonious colours"?

You can manipulate colours until they suit you
with Photoshop, Picasa, or any of many other
'brands' of photo processing software.

The D800E has held the number 1 rated sensor position in DxOMark ratings since it was introduced. It should provide great portraiture and landscape photos, as long as you have good lenses.

It takes both a camera and good lens for the highest quality photos - many people concentrate on the camera without having much thought to a good lens. So put a high-end lens in your budget along with the camera… Nikon 24-70mm f/2.8, 24mm f/1.4, 85mm f/1.4 etc.

If you stick the 18-105mm kit lens that probably came with your D7000 on the D800E, you will probably be disappointed in the results.