A bit. They do have a lot in common though (the black, browns and metallics), which helps make it work. Personally I like to have at least as many "anchor" colors as I call them like black, grey, brown and dull metallics to balance out the bright vibrant ones.
If you're mixing a lot of bright, opposing colors like this, I like to ground the colors using a common color in the mixtures. Whether it's a shade, mid or hilight, having that common ground will avoid having them look too different. For example, I'm working on a classic Warhammer Dwarf army where almost every color has Trollblood Hilight in it. The blue and dark reds are hilighted with it, the wood grain blends up to it, the white is based on it, etc. Hopefully this is making sense!
A good example is Jakob Neilsen's older stuff where just about everything always had at least a little purple in it.