On the back of the sound bar you'll find an optical, coaxial, and analog input, which is plenty if you use your TV as a switcher. There's also built-in Bluetooth for wireless streaming from mobile devices.
The S4251W includes two "wireless" surround speakers that you place in the back of your living room. They still need to be connected via wires to the subwoofer, but you avoid having to run cables from the front of your living room to the back.
The nice thing about the surround speakers is they'll give you true surround sound, which the vast majority of sound bars can't deliver.
The surround speakers use a standard RCA-style plug to connect to the subwoofer, instead of a proprietary cable type, so it's easy to get a custom length cable to fit your living room if the included cables aren't the right size.
The included wireless subwoofer doesn't need to be connected to the sound bar, but it does need to be plugged in and connected to the two surround speakers. You can place the subwoofer in the back of your living room for the cleanest setup. That's not the ideal subwoofer location for music, but it works well for games and movies.
The remote also includes a display, so you get visual feedback as to what input you're on and how loud the volume is. It's a much better location for the display than trying to squint and read a front-panel display on the sound bar from across your living room.
The Vizio also has a basic front-panel display: a series of lights along the bottom that light up and let you know how loud the volume is. Having a display on the sound bar (in addition to the remote) is nice in case you end up using a universal remote.
In addition to getting some hands-on time with the S4251W, I also had the chance to give it a listen at Vizio's showroom. I don't put too much stock in canned listening demos at trade shows, but my initial impressions were pretty positive. I'm looking forward to taking a more in-depth listen to the S4251W when it comes out this spring with a list price of $330.