I have a G5 and like it.
It has an artificial horizon page with directional info, rate of turn, and slip/skid ball, as well as a DG page.
You can set a heading bug on the DG, and it can also be driven by a Garmin nav device for a true HSI display.
A buddy of mine bought a Dynon D2 a while before the G5 came out, he likes it & thinks it's every bit as good as the G5.
Plus it can be swapped from plane to plane easier. I think the G5 looks tidier but that's just me.
The G5 is not portable, meaning that it needs some sort of approval or signoff in a certificated airplane.
Mine was installed as a minor alteration per FAA policy statement PS-ACE-23-08, which requires it to have a backup battery.
Total equipment cost was $1440: $1200 for the G5, $50 for the install kit, $20 for a circuit breaker, $150 for the backup battery, and $20 for a remote GPS antenna. I installed it all myself and an A&P buddy inspected it and did the logbook entry.
I think the Dynon D2's go for about a grand, and just clip into place.
You might still need or want an antenna & power source though.