Around back you'll see there's not much connectivity -- just an Ethernet jack and minijack input (the old-school way to listen to your phone's music), plus a headphone port on the side. The UE Smart Radio also has built-in Wi-Fi, which is a nice plus over the competing Sonos Play:3, which needs the separate Sonos Bridge to connect to your home network. Note that the UE Smart Radio needs to be connected to the Internet (even to play locally stored music), so you can't use it anywhere that doesn't have Wi-Fi. More on this later.
Streaming-media support includes Spotify, Pandora, Rhapsody, Mog, SiriusXM Internet Radio, Slacker, Last.fm, and TuneIn Internet radio. There's also support for a larger group of niche streaming-audio services; you can see the full list here. Again, it's important to note that the UE Smart Radio must explicitly have support for a service to listen to it, unlike a Bluetooth speaker that can play back audio from any app on your phone/tablet. That means if a great new streaming-audio service comes out -- call it the next Spotify -- you'll need to hope that Logitech will issue an upgrade so you can listen to it on the UE Smart Radio.
The UE Smart Radio is also capable of playing back your personal digital music collection, provided you download the UE Music Library software and have the server running on your Mac or PC. It's a bit of a hassle to need to always have your computer on in order to listen to your digital music collection, especially when there are several cloud-based music lockers (Google, Amazon, Apple) that a device like the UE Smart Radio could have drawn on to provide access to your music without a computer. That being said, the software was very easy to install (unlike the tweakier Squeezebox software) and worked great in my testing.
Squeezebox enthusiasts also have a point that the UE Smart Radio is somewhat of a downgrade from the existing Squeezebox Radio: it requires an Internet connection to play back even local media, it loses a lot of geekier customization options, and it doesn't work with the existing Squeezebox ecosystem of products. It's the classic battle of simplicity versus customizability (see: iOS versus Android), but for new customers it may well feel like overall Logitech made the right choice, as the UE Smart Radio is significantly simpler to set up and use than the Squeezebox Radio. It's a shame the company couldn't offer a simplified product that also maintained compatibility for those invested in the Squeezebox ecosystem.
Like the original Squeezebox Radio, the UE Smart Radio sounds better than it should for its small size. It's a mono-only experience (which isn't much of a drawback since stereo separation is negligible at this small size), but it's a musical speaker that sounds good with a variety of music types, from jazz to hard rock to classical.
The bass reproduction sounded surprisingly good on Bill Evans' "You Must Believe in Spring." It has just enough low-end to sound credible, but it never felt hyped or overly boomy. It also never distorted even as I cranked the volume, which is common on lesser systems. You can't expect Black Sabbath's "Master of Reality" to have the same impact it would have from full-size speakers, but the UE Smart Radio held its own, even doing a decent job with Geezer Butler's detuned, sludgy bass.
It's a good thing the UE Smart Radio is so well-tuned out of the box because Logitech doesn't offer any EQ options for adjusting the sound quality. It's a somewhat surprising move, since small systems like the UE Smart Radio can often benefit from tweaks (to account for their sensitivity to room placement), but I rarely felt the need to do any EQ tweaking during my listening.
What are the alternatives?
The most comparable system may be the Sonos Play:3, although it's considerably more expensive at $300. The Sonos software remains best-in-class, especially if you have more than one Sonos device, but it's very expensive as a standalone product, especially if you need to also buy the $50 Sonos Bridge for wireless access. For most people, the Logitech UE Smart Radio is a better value as a standalone purchase.
On the other hand, it's worth considering whether you even need a standalone "radio" like the UE Smart Radio or if you'd be better served by a simple Bluetooth speaker that relies on your smartphone to serve up music. Again, Bluetooth speakers are compatible with any music app on your phone and don't require Wi-Fi. The downside is that they don't work without your phone supplying audio, but that's not a big drawback if you always have your phone with you. And the deciding factor for many may be price; excellent Bluetooth speakers like the Logitech Bluetooth Wireless Speaker are selling for $120, compared with $180 for the UE Smart Radio.
Logitech's aim with the UE Smart Radio is clearly to take the best of the Squeezebox Radio and bring it to a broader audience by making it simpler. I'd call it a success on that level. Digital audiophiles will lament the loss of features and Squeezebox compatibility, but the UE Smart Radio is more accessible out of the box than any prior Squeezebox product.
However, many buyers will be better served by a Bluetooth speaker, like Logitech's own Bluetooth Wireless Speaker, the Soundfreaq Sound Kick SFQ-04, or the Jawbone Jambox. If you want standalone operation and your music listening doesn't revolve around your phone, the UE Smart Radio is a nice portable home-audio option, but make sure it's the best one for your own listening habits.