If you don't like default look of KDE, then you can customize it. I have some simple tricks for you and describe them shortly. WARNING: Always make copy of files your modify!
Adding Clock for login manager:
For security reasons I always disable users listing:
If you don't want to quess someone your password:
"All parts should go together without forcing. Therefore, if you can't get them together again, there must be a reason. By all means, do not use a hammer." -- IBM maintenance manual, 1975