Search for the user you created. See if he now exists as a result of your creating him.
I get the same when I create a user (brought back to New user form with no indication that the previous create succeeded). When I search for the user, the user exists, so create succeeded. It's just a usability issue (might be a bug in 4.2.c, you could raise a JIRA item around this if you want) that (1) there's no indication that the user was created and (2) "Create User" acts like "Create and Create Another". Create User should just go to a success page.
"Create and Create Another" goes back to the New User form but it does show "User created successfully" text (which fades away).