[Dremare]

Depends on what it is. But for most things, one, simple word is clear: NO.

I mean, if its something like Kamen Rider Decade (the storyline), where its SUPPOSE to crossover with the previous series in Kamen Rider, it works fine. But with Star Wars and Transformers, it doesn't. At all. I mean, the concept ITSELF is cool, but when you see it, it doesn't look remarkable at all. The same goes with the Marvel Superheroes and Transformers line.

Another example is Lilo and Stitch. They crossed over with at least two other Disney series (I think), which were American Dragon: Jake Long and Kim Possible. It sounded cool, but with the other all result, it was horribly. And you CANNOT imagine the horribleness of those Hannah Montana crossovers.....

One particular one I like more than most is the Nostalgia Critic/Angry Video Game Nerd feud. It's not really crossover, it's more of 'two nerds trading back insults and punches on the Internet' thing. That's the best part, to me, at least.

But not all crossovers are bad, just depends on how long it takes to finish the story (if it's like the Jimmy/Timmy Power Hour, though, it stinks).