It makes sense for Google to adopt Miracast given DLNA's failure to blunt AirPlay, but its adoption of the SlimPort HDMI technology in the Nexus 4 makes less sense. It brings to three the types of video-out connectors in the Android world, after the MicroHDMI port available on some devices and the MHL-compatible MicroUSB port available on some others. Like MHL, SlimPort uses the MicroUSB port but provides extra pins to transmit video, so device makers don't need a separate MicroHDMI port. But MHL cables don't work with SlimPort or vice versa.
Adding insult to injury, Google's three Nexus devices don't even use the same video-out technology: The Nexus 4 uses SlimPort HDMI, the Nexus 10 uses MicroHDMI, and the Nexus 7 has no video-out-compatible port at all. Each is made by a different manufacturer, but you'd think that Google would have made the technical requirements the same for such a core technology.
It's basic hardware, otherwiseThe other unique hardware feature in the Nexus 4 is its support for so-called wireless power (inductive charging), a dubious technology that wastes energy and requires space-gobbling mats. It's a toy, not a useful capability.
Other than LTE support, the Nexus 4 has the hardware you'd expect on a modern smartphone, including Bluetooth radio, Wi-Fi (with Wi-Fi Direct support), near-field communications (NFC) short-range radio for touch-initiated sharing and payments, front and rear cameras with rear LED flash, and audio jack. It felt perfectly responsive and didn't suffer the app crashes I experienced in the Nexus 10 tablet. The Nexus 4 is a perfectly serviceable smartphone, as long as you don't plan on using LTE while you own it.
But for the privilege of owning a middling smartphone without LTE, you'll pay much more than you would for a premium Android smartphone or iPhone. The Nexus 4 costs $300 for the anemic 8GB model and $400 for the 16GB model, versus $100 to $200 for equivalent high-end smartphones. The reason is that you're paying the full cost of the Nexus 4; the carriers don't subsidize its price as they do most smartphones. (An unsubsidized high-end smartphone can cost $550 to $650 for the equivalent storage capacity.) Even though the carriers save the subsidy costs, they don't give you a break on the service costs -- all you gain is the ability to switch carriers without paying an early termination fee, which happens to be about the same as the extra cost of the Nexus 4. The economics just don't work.