Vertigo Industries gave us an Eddy to play with...
I'm a die hard Grigri fan (15 years running) the first thing I did with the Eddy was load the rope the wrong way round (it's opposite to the G). Feeding the rope to the leader while belaying was easier with the Eddy and being able to lock it while the climber is not moving is a nice option.
When lowering a person to the ground it's harder to get them to 'freefall' as there is only +-1cm 'sweetspot' that will allow you to lower a person (obtaining freefall is possible with practice
Should you pull too hard on the lever, the device will lock up, whereas with a G the person will continue to accelerate groundward).
The lever is tucked away and there is less chance of it catching on anything in the event of a fall (making it safer). Should the belayer 'grab' the Eddy there is almost no chance of stopping the device from locking (whereas this does not hold true for the G)
The Eddy does all the jobs that the G does.
If a complete non climber had to belay me and I had an option of what device they could use... I would hand them the Eddy for sure.
The price and weight are slightly off putting... but then so is a busted ankle / hospital visit.
I'm a sentimental guy, so for now I'm gonna stick with my G (so long as I choose who is belaying me and the rope I use does not have a slippery coating)