I seem to be the only person on the planet with no trouble!
I ordered 3 sims ~ 20th December. Delivered about the 23rd.
2 of them didn't work in my wife and daughters iPhones straight as the phones were locked to ID (even though Three had unlocked them prior to our switch to ID - the unlock must have been a temporary one).
Mine was dropped into my phone (Wileyfox Storm) and just worked. As it's EE, the coverage is way better than with ID (runs on top of Three) - bits of the house that had no signal at all on ID/Three now have full 4G. Requested a number port on Monday Dec 26th, and was ported by Wed (2 working days).
Requested ID to unlock the 2 iPhones. This took ~7 days (over the Christmas break). Numbers were ported as soon as we saw the unlock messages. Port took 2 days, and we've now got 3 SIMs, all running happy with data, and no problems.
Looks like we were lucky.