I purchased Sewer Shark soon after I acquired my first Sega CD (mid 90's). The Sega CD I purchased was part of the last run of the Sega CD models, the one that had Tomcat Alley as a pack-in.
I though Sewer shark was decent, when the Sega CD was new I thought the game was pretty decent. Though, it was the type of game where after losing I would have to take a break from the game for at least a few days. It was not a game I could play over and over again trying to win. Since my Sega CD did not include this game I went to a used video game store. Sewer Shark was a pack-in game, so it was dirt cheap, I pad $5.00 or so for the game. I feel I got my money's worth.
I got pretty far in the game, almost beat it, however the lack of continues and such really wore me out on the game. I disliked getting so far into the game, only to crash into something when I missed a turn and be kicked back to the title screen.