Could not agree more, their prob is they used Hires mode (and possibly only that mode, TMR etc will know for sure) and its a bland mode so you just have to make it exciting to look at..
It looks to be running in multicolour character mode, at least based on the screenshots at their website, but that means some of the elements can be in high res since the C64 can mix and match in that mode.
The blandness is more likely down to 16K of ROM space in total. I'm guessing there's only the one set in use during play and perhaps a dozen characters taken up by the status bar (making another assumption that there's no other alphanumeric characters or graphics in there for other parts of the game like the titles page) that only leaves about 40 characters per stage. S'not a lot of work space for producing big graphical set pieces, the "bubble" level in one of the screenshots is probably getting through around 30 characters on it's own.
@TMR, you get the odd mention on here but its about 8 pages back by now , http://www.indieretronews.com/
S'funny, I follow the RSS feed for there and missed my own cameo!