As expected, I got the patch (there was only one, 3MB) and started playing.
The wall textures, basically most of the ambient textures were pretty bland, but the character models and equipment looked amazing!
Then I decided to install it, against my better judgement actually, and I lost pretty much all hand/weapon textures.
The walls and other things in view look noticeably better, at the cost of character textures.
I uninstalled and cleared the cache but unfortunately, I am stuck with the 'installed' version, it would seem.
I suppose the only other option would be to format the HDD, but that is something I'm not prepared to do.
I definitely preferred it running off the disc.