Bear in mind that we're talking about enormous 14:1 or 20:1 zooms, with massively wide short ends down to 4mm or so with the complex retrofocal design required to land that on a 3-chip block, plus extenders and relay groups to add optical junk to proceedings, which have to be small and light and often open up to a 1.3 all the way down.
No, they're often not that great and sometimes they're absolutely terrible. Many of them have horrifying amounts of flare and diffusion and horrible contrast, especially at the long end, and especially wide open. Think about news work, where the priorities are a very wide wide end, a very long long end, and the ability to form some sort of image when you can more or less count the photons going past using an abacus. "Good" is of course relative but it's not an interesting old-lens sort of artifact, it's just milkiness and glow.
This has some comparative shots of a Fuji 17x7.6 HD lens and a 20x8 SD lens on a Blackmagic cinema camera. The performance is probably compromised by the 3-chip versus single-chip issues, but the comparative improvement with the HD lens is enormous. Both, sadly, are blown away by a much cheaper Canon 100-400 stills lens, but those are the breaks if you want a real zoom.
Were all this not the case I'd probably own something like a Blackmagic pocket camera right now, rigged up like that.
Oh, and, edit: this also has relevance to stuff like Amira. They're talking about B4 lens adaptors for it (or something like the HDx35), which are probably a good idea as the Fuji Cabrios really make it far too front heavy. One wonders what B4 lens could do an Amira justice.