Got myself a HTC On Mini the other week
It's a very good phone. Good quality speakers (With decent volume), very fast and responsive, a decent amount of memory. The camera is very decent, they reduced the megapixels in order to improve various other features which overall make a better quality picture (Shutter speed, light responsiveness etc.). It's highly customisable, the only drawback is their 'blinkfeed' on the first homepage tab, which isn't removable yet on my model. Though you can remove it on the HTC One as that has the latest software update. It has a very sleek case, similar to the HTC one but has plastic edges seperating the aluminium instead of a one-piece case. The battery life is excellent, though this may be due to my obsession with turning off data connections whenever i'm not browsing the internet.
The main two drawbacks are the lack of storage (No SD card slot, only 16GB as standard, limiting for heavy music/video users) and the shape. I just can't get over the shape, it seems they went the same route Apple went with the iphone 5; a taller thinner phone. At first it's difficult to reach the top of the screen, and it's impossible to press the lock/on/off button without shifting your grip. It has the same screen size as my old HTC sensation (4.3"), but it's near half an inch taller because of the changed height/width ratio and the addition of an extra speaker on the bottom end of the phone. This bothers me so much I wish I had spent the extra to get the flagship HTC One, as they got the proportions right with that one.