Colourised - not so bad.
I recently got a great deal on the colourised dvd boxset ( 20 million / it / earth v's ) - I'd only ever seen 20 Million Miles to Earth before and it's always been one of my favourite "stop motion" oldies.
I really enjoyed the colourised version of the movie... I feared the worst, but think they've done a wonderful job. There's always the option of switching to the original b&w if you find it insufferable :)
Plenty of interesting extras included with the movie too... and I get to watch two more Harryhausen movies I've never seen before.
Good deal, with plenty of options and extras.