The form factor and weight of the iPad mini are what initially intrigued me. I never thought I’d be able to go back to a non-retina screen. My fear of the non-retina screen was not justified. I still notice the difference, especially with text, but the weight and size of the mini make up for the lacking screen.
Also of note; the screen appears to be further away from the glass. This isn’t something I noticed when I used a iPhone 3G and it’s not something I noticed when moving to the iPhone 4, though others pointed it out.
By far the biggest annoyance is the volume buttons. Apple has chosen to control volume with two discrete metal buttons. Previous iPads used a single button for volume. I like the aesthetic of the metal buttons but in moving to discrete buttons users have lost a subtle design cue. Previously I could touch the volume button and know if I would be increasing or decreasing volume. Now, without looking, when I feel a button I don’t know if it will increase or decrease volume. This should be viewed as a minor complaint and really speaks to how well thought-out the iPad mini is.