I opened my GHz Pandora to replace the LCD cable. I wouldn't say it was very hard, but it did take some amount of patience to do it without breaking the plastic (much).
Had to look for a small screw driver that fit the screws well, the standard size screw drivers (like one would use on PC screws) won't work. Luckily my bro had some I could borrow.
Once the screws are removed, the bottom of the case (where battery sits) didn't want to come off for me. There's a clip at the front of the unit (between the SD cards) which didn't want to cooperate. Had to fight with it a bit, carefully, to get it to release.
Then there was the plastic cover that's over the LCD. That one took good amounts of patience. The clips require quite a bit of force to get out. Specially the two near the first corner one tries to pop out. It took a special kind of pushing/pulling to get them to release. It takes patience to get it out right.
After that there's the whole twisting that same plastic cover to detach it from the lid's back plastic part. ED did that with such an ease, it is not. The clips at the bottom didn't want to release for me. And even when they did release, they broke the plastic a little.
So, in summary, it's not very hard, but it will take quite a bit of time and patience. It would be easy to get frustrated and try force things causing them to break.
Reassembly is a much easier process, though.