Not that great.
Although Gir's "Doom Song" is hilarious in its own aspect, you really didnt add much, as most of the songs hilarity is Zims expression after hearing it for six months and then suddenly stopping and saying "OOOH Whats that!" at earth. So the flash only took away from it im sad to say. Also Blockhead if you havent seen him already tops even Gir for total randomness and if you havent seen him hes in the series selection.