Microphone
The new microphone looks substantially different from Rock Band 1 and 2. The microphone body is longer, looks more professional and features a longer chord length. One of my biggest complaints about the old microphone is that it would distort your vocals through the TV when you would sing louder or quieter. The new microphone does a much better job of picking up these nuances.
My only gripe with the new microphone is that it doesn’t have the weight of a normal microphone. In fact, the new microphone is quite a bit lighter than the Rock Band 1 and 2 mics.
The Verdict
The new instruments feel great and what’s even better is that Rock Band 4 still supports most of your old peripherals. I even tested out one of my old third party guitars for the Playstation 3 and it worked just fine in Rock Band 4.  As a die hard Rock Band fan, it feels great to get the band back together.