I have just bought a new 6" caliper and am impressed with its build quality for a low cost tool but ergonomically its a disaster.
I have always felt that product manufacturers do not make the best thing they possibly can for the price, but instead leave off features so that they can bring out a (slightly) improved model later.
The features I think they should have is;
Auto switch on (as soon as you move the slide)
Auto off (may as well)
Well separated tactile buttons (with click)
Thumbwheel
Lithium coin cell (rather than button cell with short life)
Memory! (ie it does not need zeroing every time it is switched on)
The caliper I now have has a large LCD screen (orange, and very clear) but the two least significant digits are smaller than the rest. That's acceptable for metric but looks silly and is really confusing in imperial mode. Its buttons too are very close together and its easy to press the wrong one. Also, why on earth the designers included a fractional display defeats me, its just a waste of resource.
I've bought this one now and I will use it but I would not have done if I had tried it first rather than just seeing it on a catalogue page. Actually though its becoming the norm these days not to be able to try before you buy but to be fair shops do take thing back usually.
I will keep looking for my perfect measuring tool…
Ian