Pros: Good VRM, UEFI, voltage check points , price-perfomance
Cons: VIA Audio isn't compatible with OS X if you make a Hackintosh , USB 3.0 Marvell support spotty outside of Windows , missing 2nd heatsink, fan control
2 oz copper PCB (something missing on the Z77X-D3H, note lack of U) , Glass fabric PCB relevant for LN2 OCs
V_core adjustment in 0.005V increments
ATX4P1 for extra power to PCI-e slots
BIOS allows control of voltages and timings
BIOS / Software doesn't lie: I tested with a multimeter and the voltage is within 0.001 of what's on the BIOS screen
Best OC board under $150 : V-check points, POST code display, Power button, good VRM that doesn't use D-PAK mosfets , Dual BIOS
-> "The response of the Gigabyte board under load is fantastic. No ripple at all and a lower average voltage than the ASUS P8P77-V Pro." - Anandtech
dust covers for display outputs
VIA audio is not fully supported for Hackintosh builds (http://www.tonymacx86.com/mountain-lion-desktop-guides/68018-gigabyte-ga-z77x-ud3h-i5-3570k-hd4000-works-except-via-sound.html , http://www.tonymacx86.com/desktop-compatibility/84621-ga-z77-ud3h-build.html), although in my testing it works fine on Linux variants (Debian based and Fedora)
The VIA VL800 controls four extra USB ports on the back of the board, and these don't work without drivers. This means it is spotty outside of Windows.
Fan control is rudimentary due to the SuperIO. Your 4th fan is full speed, fans 1-3 are all linked together in RPM ramp up. Unlike some ASUS boards you cannot run more than 1 fan on the CPU fan header without a splitter.
ASUS' Q-connector thing is gimmicky, but it would save time (about 5 minutes) if they included something similar.
If you use the mSATA port you lose a SATA port
people complain clear CMOS and reset are too close together but I don't have stubby fingers
The 3D BIOs has one use for me, to adjust voltages and speeds quicker instead of using Page Up/Page down
A comparable board from Asus costs you $170+ (P8Z77-V Pro) and for that mone you could grab a GA-Z77X-UP4 TH or GA-Z77X-UP5 TH with Ultra Durable 5, which uses 60A capable IR3550 PowIR stage.
ASUS P8Z77-V LX/LK/LE (4+1 VRM of lower quality components) / AsRock Extreme 4 (D-Pak mosfets) are lame in comparison. It has equal or better performance than the P8Z77-V Pro from ASUS.
If they changed out the SuperIO to something that can control fans independently this would be fantastic (at least in Windows , go UD5H /UP5 TH for native OSX and Linux).