I think it's a fair thing to say that iteration and expansion on existing ideas, even if they're someone else's, is a legitimate form of game design. It's a fine line though, especially when you go with an aesthetic that leers very close to that of your ludological muse. Puzzle de Bowling iterates upon the Puzzle Bobble series with a couple of its own ideas, but as inferred, I think making it look so much like Taito's games was a big mistake that gives it the air of a shameless mockbuster.
Like you've probably inferred, Puzzle de Bowling is a lot like Puzzle Bobble, but with a bowling theme. Also, the characters are cute anthropomorphised signs of the zodiac. There's a bunch of different-coloured bowling pins at the top of the field, and you roll different-coloured bowling balls at them. When the balls stop moving, they become pins, and if this results in three or more pins of the same colour touching, they'll vanish, and any other-coloured pins hanging off of them wil fall off, too. If you manage to get lots of pins in one go, you can get strike and split bonuses.
The mechanical quirks come from the bowling theme. There's gutters at either side of the field, and you can get a gutterball, though I'm not sure of what the penalty is for doing this. It can get balls of unwanted colours out of the way, at least. The big one, though, is the way you can put a little curve on the ball. As well as moving your character left and right along the bottom of the field with the joystick, there are three buttons related to controlling the ball. Before you roll it, you can press the left and right buttons to determine a point at which the ball will veer in the respective direction. So you can get the ball into awkward little nooks that would require a difficult trick shot in Puzzle Bobble.
It sounds like it's an ability that would make the game far too easy, but it doesn't work out like that in practice. The puzzles in the solo puzzle mode are designed in such a way that though the curving system is very helpful, it won't get you out of every jam, and the weakness it has in versus mode is that it does take a couple of seconds longer to line up a perfect curved shot than an okay straight one. I'm sure with practice, high level players could theoretically be able to play accurately at high speed. But, obviously, this game is so forgotten, it's very unlikely that there are any high-level players anywhere in the world. Especially since its only home port was cancelled before release.
Anyway, and I feel like this is something I've said about other puzzle games in the past, Puzzle de Bowling is a decent enough game. It's fun to play, and like I said, its lack of originality isn't too much of a black mark, as it's obvious that the developers had an idea they wanted to try out that was an iteration on an existing one, and that's fine. The aesthetics, though, feel a bit cheap. The character designs are incredibly generic, and if you put the characters in Puzzle de Bowling up against those in its contemporaries like Magical Drop 3 or Puchi Charat, they're just lacking a certain intangible something to make them appealing. But here's the part I'm sure I've said before: the later nineties were an amazing time for puzzle games, and lots of really excellent titles were coming out. So why would you ever play this one over any of the others? It just isn't as good or as interesting or as exciting as any of them. Give it a shot in MAME if you're curious, but don't expect it to stick with you.