Very thorough review, thank you for using pictures. I hope your follow up review says that the buttons get easier with time!
I got more used to the Plus and Minus buttons by now and when you know just the right amount of pressure is needed, it's not as bad, except for the button in the middle. It's always going to be difficult pushing on it, only because it's tricky to get it right.
We have one, and my wife loves it. It is right up there with her favorite toys now and we've only had it about a month. Good, rumbly vibrations really do it for her.
We did love this toy, but a few months ago it stopped working. I won this, so I would consider it bad form to try and have it replaced even though there's a warranty, so now it's serving as a very pretty dildo for us.