We bought the new rotary lock version of this cat flap for our two kittens who promptly got used to it and it worked excellently keeping out neighbouring cats. However, after two months it stopped working. I phoned up Sureflap and they sent out a new lock which didn't solve the problem. Following another call they sent out a new cat flap and after installing the new one sent the old one back.
The new flap works fine although there is a good 3 - 4 second delay before the flap unlocks whereas the previous one unlocked as soon as the kitten entered the casing. Whether this is due to the sensor not immediately detecting the presence of a cat or not, I do not know. However, as the kittens got used to the first cat flap, they just tap on the flap a few times waiting for it to unlock and can use it without any problems, which is why I haven't bothered having it replaced again.
Some people have mentioned the clicking, but this may be on older versions, there is only one click on this which is when it unlocks or locks, but this provides a good indicator for the kittens to know when it has unlocked and can go in. It would probably be difficult for a cat to get used to Sureflap for the first time with a delayed unlocking and if this is the case I would definitely seek a replacement.
I would give Sureflap 10/10 for customer service as they dealt with my query simply and swiftly but they need to work on reliability. Although there is a two year guarantee, a reliable cat flap would provide more peace of mind as I am continually checking it works ok. I am going on holiday soon and although will they be feed and kept an eye one by a neighbour I am concerned that the cat flap will fail again and lock the kittens outside.