Seaman is a tough game to review. Since the overwhelming majority of titles released these days are rehashes of games that have been done time and time again, a rare gem brimming with originality is something to be cherished. Overall I found it to be a very worthwhile and interesting experience that has never really been done before. On the other hand, Seaman isn't really a "game," so I'm sure that a title like this isn't going to be to everyone's liking.
Graphically, the game is nothing special whatsoever. While I do like the design of Seaman himself and find him to be a very memorable character, the environments are simple to the extreme and fairly boring. It's not exciting to look at, and you have nearly no control over the environment whatsoever. Call me crazy, but I would have loved to put a little plastic castle or mermaid in the tank to make things just a hair more thrilling. Despite the flat black backgrounds and empty aquarium, there are still some clipping and collision problems as well (though nothing major).
Graphical issues aside, the real reason people would play Seaman is for the conversation and interaction with the weird fish-thing. Here is where the meat of the game is, yet it's might not quite enough to satisfy. After Seaman gains the ability to speak there are some very interesting, possibly risque things he has to say, but the limitations of the game's structure are fairly obvious. He'll ask you some questions and based on your replies, he will go off on various tangents. However, you can't really make him talk about anything in particular. He talks about what he feels like and your answers are limited to one or two word responses. This is fairly entertaining in itself, but the voice recognition software is pretty spotty when you try to talk about something "off-topic" from what Seaman is interested in at the time. Also, when he asks you questions, I'd estimate the game can recognize about 80 percent or better of the possible responses, yet the few times it it failed to understand my answers were fairly frustrating.
The last thing I had a problem with was the extremely slow nature of the game. As Chi mentioned, this is more of a digital pet than traditional game, and along with that comes a higher level of patience necessary. Once Seaman is mature, he tends to only want to talk once or twice a day, so for the other 23 hours and 45 minutes there's nothing going on in the tank. Coupled with the sparse pace of conversations, the game is designed to be played over the course of a month. Unless you cheat the Dreamcast internal clock (as I did) , there's no way to make things go any faster or to speed up the process. Hence, if you are buying Seaman as something to keep you busy for hours at a time, it won't be very fulfilling. Seaman is something best played for 10 minutes at a time during breaks from other games.
If the negatives I've mentioned haven't turned you off by now, then you are probably the type of person who will find Seaman to be a very enjoyable and original experience (as I did). If I had to score Seaman on it's concept and freshness alone, it would easily earn a perfect 10. However, as I already stated, it's not really a "game," so I think it's pretty important to have an open mind before purchasing. If you're looking for something new and fresh, this is it. I definitely give Sega the highest respect possible for taking a risk with a game like Seaman, and I hope they do it again in the future.