I'm under the impression UK stores like the DVD packaging so they can get more on the shelf and minimise stock space. Pretty much everyone I know prefers the DVD packaging anyway, they're less bulky and fit into shelves/DVD racks etc. Giant boxes are a PITA (ok a minor one, but hey the solution seems to be better for everyone anyway).
I take it that having installed Steam etc with the UK retail HL2 (standard version), I cant just install my old HL1 'GOTY' and have Steam import it and Source-ify it?
Overall verdict for HL2 so far (i'm at the prison seen in one of the more famous vids - hardly a spoiler but playing it safe), it delivers. Graphics are (imo) bettered by Far Cry, nevermind DOOM3, but the gameplay is good with lots of variation. Most importantly, it's a "superb gaming experience", even if that does make it sound like i've read so much PR pap that's its overflowing out of my mouth.