Despite having made the journey from a smartwatch skeptic to an Apple Watch convert, I was – until very recently – still using my original model, aka the Series 0. It had become something I wear every day, and now wouldn’t want to be without, and Apple hadn’t shown me any reason to upgrade.

When the Series 2 was launched, I concluded that despite the improvements it offered in some areas, there would be no benefit to me given the four things for which I use it.

The Series 3 is, of course, a much bigger upgrade, but I was fairly sure that wasn’t going to persuade me either …

The biggest new feature, of course, was the LTE functionality of the more expensive model. For the first time, the Apple Watch could – once activated – be used independently of an iPhone.

I do see that as an important step in the evolution of the Watch, and one that offers real benefits to some people in some circumstances.

If you’re a jogger, for example, it’s great to be able to leave your phone at home and run unencumbered, while still remaining reachable in emergency. Hitting the beach or hotel pool are other situations where you might want to leave your phone in your hotel room or car. The gym is another obvious example of when it would be good to leave your phone in your locker.

But I cycle rather than run, prefer active holidays to beaches, and favor absolutely anything else at all over the gym. I literally can’t think of anywhere I’d go without my iPhone other than scuba-diving, and an Apple Watch would be a hunk of scrap metal 60 feet beneath the surface.

So for me, the LTE model wasn’t relevant, and I initially saw no reason to upgrade to the GPS-only model. I’d always said that I’d wait for a slimmer model before I upgraded. But two other enhancements then caught my eye …

The first, which Zac reported in his review, was ‘dramatically improved Siri’ performance.

I’m a massive Siri fan, and it’s one of the main ways I interact with both my Watch and my iPhone. I dictate most texts, voice most of my search requests and even ask Siri to open apps. Any notable improvement to Siri is a big deal to me.

It turns out it was a performance restraint and not a design decision, and the Apple Watch Series 3 remedies that. Seeing your words appear as text as you speak and trusting Siri to quickly respond when you glance away dramatically improves the reliability of the experience.

Voice feedback is good – it’s an easier way to interact with Siri on the move – but the responsiveness was the bigger draw for me. With my Series 0, I would very often see the ‘I’ll tap you when I’m ready’ message. Zac said that he only saw that once, and then only for a split second. That was already starting to sell it to me.

Then there was the new heart-rate functionality. I may not do gyms, but I do care about health and fitness, and resting heart-rate is a very good guide to overall fitness level. The Series 0 was the only watch not to support automatic monitoring of resting heart-rate, along with the time it takes to return to that rate after exercise. That gave a second justification for an upgrade.

Finally, there was the upgrade cost. Since I wasn’t interested in the LTE model, and the GPS-only model surprised us all by actually being cheaper than the Series 2 it replaced, this was lower than expected.

I’ve written before about how the so-called ‘Apple tax’ is lower than it appears thanks to longevity of products and consequent high resale values. A quick check of eBay completed sales showed that my Series 0 watch was going to be worth around half the cost of the Series 3 GPS. That put the upgrade cost at a level where it was easy to justify.

I did briefly toy with buying the LTE version despite the fact that I had no use for the added functionality. The cost difference wasn’t that great, and I wondered whether it might be better to have a feature I’d never use than to find myself wishing for it later. Especially as the resale value would take care of half the difference.

Had that been a simple one-off cost, I might have made that call. But as it would also involve a monthly cost, I just couldn’t see that I’d ever use it. Small as the true cost difference might be, for me it was just going to be wasted money.

My Series 3 arrived yesterday, and I’m already convinced that the boost to Siri responsiveness makes it a worthwhile purchase. If I find any other benefits, I’ll update with a new diary piece later. In the meantime, I’ll be putting my trusty Series 0 up for sale.