1. He's a minibot
2. He transforms into a hovercraft. Hovercrafts are cool.
3. His voice in the cartoon. Provided by the amazing Alan Oppenheimer (who voiced Skeletor, which is cool), Seapray actually gargled when he spoke, making his voice sound bubbly and sea-like. This is very cool (although a bit tough on the vocal chords when trying to imitate).
4. His job is 'Naval Defence'. He's a naval tactician. This is cool.
That's all the convincing you need, right? No?
Ok then. How about the fact that his Tech Specs don't have the usual guff like 'has to stay at sea, and is therefore morose and lonely'? Seaspray LOVES his job, keeping the waterways clean and well-defended. Unlike plenty, if not all, other bots in a similar position, Seaspray doesn't get down about not being part of the 'main' team, as it were. What he does is just as important as what they do, and that's enough for him. That's pretty cool.
Seaspray also got one of the strangest episodes of the cartoon to himself too. Sea Change involves aquatic aliens, a rogue Cybertronian robot, and Rumble being transmogrified into a tree. No, seriously. Watch the episode at the end of the blog and find out for yourself.
Seaspray's a bit different to the other minibots. He's aquatic and not a car, he's a little bit funkier. He's also a lot happier than many Autobots, having been given a job to do that he actually enjoys, even though it keeps him away from the others for long periods of time. Seaspray is a breath of fresh air, both as a toy, and as a character, and for that alone, I think he is very, very, cool.