It's a great tool for front end testing. However, it's limited with some newer stuff - shadow DOM objects are meant to be supported since January but in reality it's...difficult. However, the way it interfaces with browsers IMHO is preferable to say, CodedUI, which takes control of the mouse and keyboard to execute tests.<p>Saying that, in Java/C#, Selenium is still easily my preferred tool, and the demand from companies/recruiters (I'm switching contracts at present) seems to indicate it's still very much <i>the</i> tool.
We use selenium tests as a last line of defense. Using it as your only integration test, however, seems a bad idea to me. There are more specific and faster possibilities for testing.<p>The thing that would make selenium a lot better, would be if browser vendors could agree on a standard for instrumentation. This is of course a perfect-world line of thinking.