I've had mine for a couple of days now.
I'm happy with it but I do find myself cycling through the menu's thinking either "played it to death" or "haven't time for that now".
I will definately hack it eventually but I'm waiting for confirmation of a stable idiot proof way.
I'm also still a little confused by the display options. I've found CRT to look the most authentic but a little too blurry at times. The other two 4:3 and Pixel Perfect don't seem quite right to my eyes. The first is too clean and the second is crisper but the scale seems off somehow.
One thing that has impressed me is the vibrancy of the colours which I don't think I've ever seen in such detail before. Especially in something like F-Zero.
I love that we have the 60hz roms but it is a little odd when, for example, Kirby tells me that I should "press those purple things" and I'm holding a controller with the regular PAL/SFX colours.
Played about 5 minutes of Starfox 2 and wasn't impressed. Will have to give it a longer burst soon. Spent the most time on Super Mario Kart so far. Luigi is still a cheating bastard!