[Xperia Z3 Compact General] v0n:
Agree with other posters regarding default vibration level being weak and max speaker volume being underwhelming (it's also very bright sounding, which adds to weakness).

Opening camera always greets me with "Recording In progress in another app. Cannot record."

Sony migration tool cannot import anything other than pictures and app data from iPhone via USB cable (method suggested by app). Use USB connection to pair your Z3C with iPhone, then disconnect it, ignore cable suggestion and go via wi-fi - then it imports contacts, sms, etc etc. All of the imported pictures were unreadable at first (picture of broken image on all pics in Photos and Album), but after entire night I woke up in the morning to both apps full of working pics, looks like it needs to read and cache something before it's able to show imported pictures.

My X3 Compact seems to hate my Netgear DGN1000 wifi router with any settings. It has no problem detecting LAN layout correctly all the time (checked with Fing), but occasionally stops connecting to outside websites with full signal strength and uninterrupted connection to LAN. When it does so, there is just no way to force it to regain internet connection, tried changing DNS, give it static IP, change encryption etc, all to no avail, when it stalls, it stalls, then few hours later it just regains routing like nothing happened). No such issues on Motorola G or iPhone in the same time when Z3C goes loopy. It also seems to prefer connecting to secondary repeater in my garden studio rather than primary router literally 10 inches away from it (which beside being weak and unstable actually always works with Z3C when it comes to outside world connection). This suggests to me some weird incompatibility between Z3C and netgear only.

Car docks/cradles. Sony doesn't manufacture powered/active car dock and button layout on the Z3C makes it super hard to find any reasonable universal car cradle for it. Landscape mode is borderline impossible, because the cradle would have to be almost made to measure and hold the phone only by the tips of corners for you to be able to attach magnetic charger and headphone jack (and you will need output to AUX or external speaker with internal speaker that quiet and weedy) and not block or press any keys on either side of the phone. Any portrait mode holders will have to be shallow design, hold the phone centrally on the top with fully open sides. Judging by magnetic charger designs I've seen so far, it might be very hard to find one usable in the car with any bumper or case on the phone.

Desktop docks. Bought DK48 magnetic desktop dock, but it's a joke. Comes with no cable, doesn't seem to work when powered from computer USB port, mine works only if powered with power socket -> USB cable, but aligning phone with magnetic connectors is so fiddly and unstable I'm close to chucking it against the wall every time I use it.

More of a platform issue than phone itself, but I don't seem to be able to find any app that would work as a network file browser with macs, neither AFS nor Samba connections seem to work on my LAN, most apps however have no problem connecting to linux samba shares...