I have just joined the masses with Apple Pay. I got my first Apple Pay compatible phone (iPhone SE) yesterday and the same evening my first Apple Pay compatible card (American Express Platinum) was waiting for me on the doormat. Adding it to my phone was simple, using it has been equally easy. I have (on advice from friends who have been using it for months) always pre-empted the transaction so far (from the lock screen double tap the home button to bring Wallet to the front, rest your finger on the Touch ID sensor to pre-authorise the transaction before being presented with the terminal and then hold it to the contactless pad when offered it) and it has worked flawlessly every time.
As for security, it depends on your trust and how much you like Apple. Apple say they do not store your actual card details (technically they do receive them on their servers but immediately re-encrypt them and send them on to your card provider or their chosen provisioning/token service provider) and therefore cannot provide your actual card details to the merchant. Instead a device specific account number is generated (per Apple device) and a different dynamic security code (per transaction) is used for each and every transaction. If someone steals your details on transaction one they're useless for transaction two. Apple get a cut from each transaction made using Apple Pay (just the same as Visa, MasterCard or American Express do) so every time you use Apple Pay you're dropping a tiny fraction of that payment into Apple's coffers. Personally this does not bother me, however I have a friend who because of this very reason will not use Apple Pay - horses for courses. If you're the sort of person who keeps their cash in a shoe box under the bed then, well, you're probably not reading this thread are you
As for your comment about the reliability of the Touch ID sensor - mine (across two years of an iPhone 5s and a day of an iPhone SE) is flawless (unless my hands are sweaty, wet from doing the dishes or I'm just out of the shower), however my friend who has an iPhone 6 plus finds she cannot use Touch ID. I suspect her issues are rooted elsewhere but I can't ignore the fact she would find Apple Pay unusable right now. If you find unlocking the phone with Touch ID troublesome then I strongly suggest you pre-empt the transaction as described above to save embarrassment at the terminal and wonder if you'll perhaps find it too troublesome in the long run?
Moving on to your final questions,
Do I like it? - ABSOLUTELY
Have I tried it? - So far three times, tomorrow is my first real day out with it (so far just been showing off/annoying the staff at my local pub with it)
Have I given up on it? - Nope!
My own add-ons,
Will I use it for every transaction? - Unlikely, I bank with Barclays who are the only major UK bank to STILL not support Apple Pay. My only Apple Pay compatible card is American Express and not all merchants accept it. Also most (all?) places in the UK only allow contactless transactions up to £30 in the UK despite Apple Pay having a higher limit at the retailers discretion.
I would strongly recommend always carrying your actual card with you for when Apple Pay fails (normally when the terminal decides it doesn't like it) and/or a backup card from another provider just in case (I have always carried a Visa and a MasterCard card with me, now I have AmEx too but will probably ditch one of my other cards shortly).
Alec
edit: Fixed my statement about Apple not getting your card details - they do but (claim) not to keep them.