Java mocking is dominated by expect-run-verify libraries like EasyMock or jMock. Mockito offers simpler and more intuitive approach: you ask questions about interactions after execution. Using mockito, you can verify what you want. Using expect-run-verify libraries you are often forced to look after irrelevant interactions.
No expect-run-verify also means that Mockito mocks are often ready without expensive setup upfront. They aim to be transparent and let the developer to focus on testing selected behavior rather than absorb attention.
Mockito has very slim API, almost no time is needed to start mocking. There is only one kind of mock, there is only one way of creating mocks. Just remember that stubbing goes before execution, verifications of interactions go afterwards. You'll soon notice how natural is that kind of mocking when TDD-ing java code.
Mockito has similar syntax to EasyMock, therefore you can refactor safely. Mockito doesn't understand the notion of 'expectation'. There is only stubbing and verifications.
Mockito implements what Gerard Meszaros calls a Test Spy.
Easier than Easy Mock
Appears to be less complete than Powermock...
Easy, simple and intuitive. Especially take a look at @InjectMocks and @Mock if You're Spring user.
Easy to use mock framework with a well designed API.
Very easy, intuitive and feature-full. I use it along with Powermock (when needed) and Fest assert and it gives me a complete unit testing workshop.
Readable unit tests, well documented with practical hints, a lot of examples, mocking is easy and powered by Brice.