Are you really using JUnit during your development?

I've written JUnit cases for over 1 month.

I have to say it's fun to do the implement coding. But it's suffering to write JUnit cases. Because:
1. I need to know the correct result from the other way around and sometimes it's hard to find another way.
2. Database and JSP pages are difficult to JUnit test.
3. Mock objects brings more than double efforts during the whole develop process.
4. Exception situation is not so easy to make as JUnit claims.

3 friends in 3 different companies (small size and middle size company) complain JUnit as:
1. They planned JUnit testing firstly and they cannot keep it going. TIME reason?
2. It consumes a lot of time but hard to find big problems. JUnit does find small problems as we expected.
3. JUnit testing is not effcient enough.
4. Best JUnit tester is the senior software developer. But senior guys hate to write test cases.
5. For small company, it's really hard to choose between JUnit+develop and develop+functional testing.

Is there anyone who is successful in deploying JUnit during develop as: JUnit + code + JUnit + code + System Testing?