It completely depends how you use it. There's so much misuse of it out there I can understand why people hate it so much. But done right it's an extremely valuable collaboration tool.

I'd recommend the Cucumber Book if you want to read about how to use it well:

http://pragprog.com/book/hwcuc/the-cucumber-book

I've also blogged a lot about how to use Cucumber well here:

http://chrismdp.com/tag/cucumber