It's well built. Weighs 36g only. It comes with a storage bag.
Diopter adjustment is hidden beneath the viewfinder.
There are 1.4 million dots compared to 1.53 millions on the GH2. The resolution is high enough to see your subjects in focus comfortably. Refresh rate is pretty similar to GH2 also. Coverage is 100%.
The image quality is good. There's some highlight clipping at times but it's a non-issue if you're using it for composition. Night images still have the noise, again a very minor issue.
There's no eye sensor. The minor inconvenience comes when you want review photos you just took on the LCD, and you have to switch it from LVF to LCD. Imagine that for the many photos you take. You can, of course, review the photo directly on the LVF which is what I usually do. The bigger inconvenience comes when you need to change menu settings, which is more comfortable with your eyes off the viewfinder. That's if you change settings a lot or want to review lots of pictures at one go.
With the viewfinder, it gives a firmer hold even with one hand, compared to two hands without the viewfinder. That's a major plus for getting sharper photos due to lack of hand shake.