Hmm.......no, it's not bad, unless you're trying to get to work on time, and you don't have a watch!
Personally, i've never seen an Opel with a working clock (of course there aren't many around these parts. Mine doesn't work either.
Mechanically, the work no working has absolutely no impact on the performance of the vehicle, but if it's really bugging you,
EBay has a set a gauges for bid starting at $5.50, including clock, fuel gauge and oil/temp. Here's the address: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?viewItem&item=1857466405