The key factor
Those are minor quibbles. The bigger problem with the Ultrathin mini is that typing on it is simply not a good experience. While fitting a keyboard into a cover with the footprint of an iPad mini means making tradeoffs, Logitech has made compromises that, for this touch-typist, are unacceptable.
On the good side, many of the keys on the Ultrathin mini are nearly full-sized--namely, all the letters of the alphabet. The Spacebar is large enough to remain within reach of either thumb. Standard nibs on the F and J keys help keep your fingers in the right places, and I like the feel of the membrane-scissor type keys themselves.
To make the keyboard "mini," however, the keys are cramped, and the key layout is frustratingly flawed. There are missing keys, tiny keys, and very tiny keys. As I mentioned, tradeoffs are necessary with compact keyboards, especially when you try to keep the main alphabet keys a manageable size, but I'm not convinced that the tradeoffs on display with the Ultrathin mini are the best ones.
For example, a number of standard keys are missing, with their functions only accessible by holding down the Fn key (located in the now-standard position in the lower-left corner) along with other keys: The A key does double-duty as Caps Lock; the Q doubles as Tab. And the Shift keys are small--barely a fraction of an inch wider than the letter keys. The combined effect of tiny Shift keys and missing Caps Lock and Tab keys is an abrupt left edge to the keyboard that, if you're a touch-typist, makes it difficult to keep your fingers in place as you type: You'll find that your hand marches steadily to the left as you use your pinky on the (tiny) left Shift key. At least I did.
I mentioned that the space between keys is cramped, but the bigger issue is that many of the non-letter keys are too small. Certain punctuation keys (colon/semicolon, apostrophe/quote, and brackets, to name a few), are comically narrow, with the number keys and Delete key barely larger than Tic-Tacs, making them difficult to type and making it far too easy to hit the wrong key instead. (The number keys present less of an issue than the Delete key, which I tended to use a lot with the Ultrathin mini--I found it difficult to press reliably.) And even when I was able to consistently I hit these little keys correctly, precisely aiming for the tiny targets often required me to take my fingers off the home row.
The result all these drawbacks is that I found typing on the Ultrathin mini to be an exercise in frustration. Which is a shame, considering how good the original Ultrathin keyboard is: I can type 120 words per minute on the original Ultrathin keyboard with great accuracy. My error-ridden speed using the Ultrathin mini was in the low 30s.
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