I've had the Ottorbox since December. Make sure it is locked into belt carrier or it will fall out. Mine has fallen out several times on concrete, thankfully no damage so it does it's job of protecting the phone. The screen protector is really thick making it difficult navigating on the phone but I've gotten used to it. The screen protector also leaves a big gap at the top that will let in dust and dirt. You have to periodically take it apart to clean the junk off. No problem with microphone or speakers. I'm waiting to see if someone will make a better case, but in the meantime, I'm staying with the Ottorbox.
BTW, it does add some bulk and weight to the phone, but I have no problem with that.