It's finally here: Apple Pay arrived on Monday as part of iOS 8.1, which turns the iPhone 6 and iPhone 6 Plus into mobile payment machines. Just install the update, add a credit card to Passbook, and you're good to start buying stuff with your iPhone.

At least that's the theory, but is it really that convenient? We decided to check out how Apple Pay works in the real world by adding cards from various banks and using it at a few retailers and services in New York City. The result: it's definitely more convenient than a credit card, but there's room for improvement.

Getting started

After downloading iOS 8.1 and launching Passbook, the option to enter a credit or debit card shows up prominently. Tap it, and you'll immediately be asked whether you want to connect the credit card associated with your Apple ID or enter a new one. However, once I connected a scanned card to Apple Pay, the option to add one from my Apple ID disappeared.

Entering a credit card number is easy — at least easier than the process most websites require, which typically involves inputting shipping and billing addresses. Apple Pay just needs the card info — you can either scan the card or input the information manually (the 3-digit security code is always manual entry).

Oddly, Apple Pay isn't able to scan vertical cards (Chase Slate account owners, start your whining now). Instead, you'll have to enter those account details manually.

Apple has deals with several banks that connect with Apple Pay, but the verification process can vary. Chase confirms the card entry with a one-time code sent to the email or phone number in the bank's files — the same process it uses for two-factor authentication. Bank of America requires the user to call customer service, which can take much longer. For us, connecting the Chase card took about 10 seconds; for BoA, it was about five minutes.

Field test

I first took Apple Pay for a spin at one of Apple's named partners for Apple Pay, McDonald's. Ordering an apple pie seemed nothing if not apt, and once the clerk rang it up, I touched my iPhone 6, still in standby, to the touchless terminal, which looked like it was a few years old.

Immediately, the screen lit up on my iPhone with both the credit card icon and an indicator saying Touch ID was required. I put my thumb on the sensor and, after a couple of tries, paid for the apple pie instantly.

It felt pretty cool, so I did it again. Soon I had four apple pies (and a somewhat bemused McDonald's worker) on my hands. The process at McDonald's was like straight out of the original demo video Tim Cook showed in September (the one where he exclaimed, "That's it!") — there was no extra step, no redundant screen, nothing.

The experience at Duane Reade and Walgreens drug stores wasn't quite as seamless, but it was still pretty good. Before I could use Apple Pay, each clerk asked if I wanted to use my loyalty card. This highlights one of the weaknesses of Apple Pay — it doesn't integrate with loyalty cards (at least not yet), so you need to present those in another step.

After I did that, I did the same motion of holding my dormant iPhone up to the terminal, and again held my finger to the Touch ID sensor, but this time there was a twist: for both Duane Reade and Walgreens, I was asked to verify the total and press "OK" on the store's terminal before the transaction was finished.

It's not a huge inconvenience, although it does add an extra step to the process that's arguably redundant (at least to the customer) — one McDonald's didn't have.

Finally, it was time to head back to the office, so I grabbed a cab. After entering, I noticed the payment terminal wasn't the standard one on so many NYC taxis, so I feared it wouldn't work with Apple Pay. But then I was pleasantly surprised to have the payment go through immediately when I tried to use it.

The fact that Apple Pay works with a New York taxi at all is a little unexpected, but it makes sense. Retailers don't need to perform any kind of update to accept Apple Pay at stores; to them, it's just another credit card number (albeit one randomized via a tokenization process). That means Apple Pay could work in any number of places Apple hasn't named.

I noticed the payment terminal in the cab wasn't the standard type, which might have been why I was never presented with the option to tip the driver. I took a ride in another cab, this time with a typical terminal, and I couldn't use Apple Pay until after I selected a tip amount. Once I did, though, it was smooth sailing — tap, scan and done.

Final thoughts

Some might argue the convenience Apple Pay offers is minimal, since it still requires you pull something out of your pocket to buy something, but that overlooks a simple reality: chances are, you have your phone out anyway. Apple Pay just adds a postscript to what we're all naturally doing, which is scrolling on our smartphones.

To really deliver on its promise, though, the service needs to integrate loyalty cards, and it would help if Touch ID got a little more reliable. But Apple's vision of electronic payments is convenient, fast and reliable. Apple Pay is for real.