The microphone icon has been removed from the address bar and it's now placed prominently next to the keyboard. If you start using the keyboard, the voice search button is replaced by some keys that are useful when you enter a web address: ":", ".", "-", "/" and a ".com" button.
Google now shows the words from your question as you speak, so you can see much faster if Google's speech-to-text engine understands what you're saying.
You'll hear the answer and Google will also show a card with more information. Spoken feedback can be disabled from the settings page: go to the voice search section and disable "speak answers back". "The answer can be a fact, weather condition, stock price, flight status, sports score, currency conversion, mathematical calculation, and more. Spoken answers are only supported in English at this time," informs Google.
Voice search is more useful as a Chrome feature than as a feature of the Google Search app, especially if you're already using Chrome. You don't have to open a new app and you can see the results for multiple questions because Chrome has tabs.
For some reason, Chrome for Android still includes the old voice search, but that should change in the near future.