Until last year's Apple Watch Series 3, there wasn't a single wearable on the market that I'd wear for an extended period of time. After a week, or maybe a month, I'd get tired of the smart watch or fitness tracker and leave it in a dresser somewhere.

Then I got addicted to the Apple Watch and what it offers. I began to rely on it for dictating a quick text to my wife while driving, for directions while walking around the city and for tracking workouts.

The Apple Watch Series 4, and new watchOS 5 software that's rolling out to older Apple Watch models, continues to build on Apple's already fantastic smart watch and fitness tracker.

There's a lot you need to know about the Apple Watch Series 4, including the differences with the Series 3 that Apple will continue to sell, so let's dive in.

The first thing you'll notice with the Series 4 is the big screen. It's larger than any other Apple Watch.

There are still two sizes, but Apple is selling a 44 mm model and a 40 mm model this year instead of the old sizes of 42 mm and 38 mm. I love the larger screen — it's much easier to see. Apple takes advantage of this with new watch faces that show a ton of info, like the weather, the time, the date, your heart rate and shortcuts to Apple Music. You can customize all of this through what Apple calls "complications" — or the tiny bits of info that appear on the watch face.

Even tasks like entering my passcode are so much easier, since the buttons are larger.

But it still feels right — I never felt that it was "too big," as I have with almost every other smart watch I've tested.

There are a few other upgrades from previous versions of the watch as well. The speakers are louder, which was convenient for hearing Siri when I asked her sports scores, and Apple moved the microphones so it's easier for people to hear you during a phone call.

I tested the GPS and Cellular model, which can continue to stream music to headphones, place calls and send text messages even when you're away from your iPhone. This worked well, and the watch seemed to transfer over to cellular faster than last year's model, which had a delay.

The battery life is good, too. Apple advertises 18 hours of use. I took the Apple Watch Series 4 off of the charger on Friday morning. I drove to the beach that evening and realized I'd forgotten my charger. I turned it off Saturday night and still had 16 percent left on Sunday at 3 p.m. I'd worn the Apple Watch all day each day, and even used it to track workouts and make sure I closed all of my rings. That's good enough for me.

I like the new digital crown on the side, which is used to navigate around apps. It provides haptic feedback — a little buzz — when you twist it, and you can press it to make a selection. Also, the button below it that brings up the app tray is now more flush with the rest of the body, which is just a tiny aesthetic enhancement.

At its launch event last week, Apple showed off a new electrocardiogram feature that exists inside the digital crown, but it's not active right now. Apple will release a software update that will enable it later this year, but when it works it'll let you take an EKG and send it off to your doctor via PDF.

The new software for Apple Watch has a lot of fun new features that will land on older Apple Watch models.

It has automatic workout tracking, for example, but it can take a bit to kick in. After about a third of a mile it asked if I was running and if I wanted to record my workout. I confirmed I was jogging indoors, and it gave me back credit for the distance I had already run, which was really neat.

The watchOS 5 system also has a new walkie-talkie option that lets you talk to other Apple Watch owners on the fly, just like a normal walkie-talkie, but I didn't have any friends who had the new software or a new watch, so I couldn't test it.

I love the new Apple Watch faces that are in watchOS 5, and many were designed to take advantage of the larger display on the new edition. There's one mode that looks like the Apple Watch face is burning, which just looks cool. But my favorite one lets me set 8 different complications, so I can quickly do things like access the exercise app, the weather and check my heart rate.

Another neat feature inside watchOS 5 on the new Apple Watch is automatic fall detection. It's off by default, but when I turned it on, it recognized when I fell on the ground and delivered an alert that said it would dial 911 after 60 seconds. I confirmed I fell and closed the notification, but you can see how valuable this would be for the elderly or people with epilepsy or similar health issues.

The Apple Watch Series 4 is super expensive, especially if you want the larger screen and cellular.

It starts at $399 with GPS and a 40 mm screen, but I like the model I tested, which has the larger 44 mm screen and cellular. That costs $529, even with the generic rubber wrist strap and aluminum casing. If you want the better-looking stainless steel case and sapphire display, which is more resistant to scratching, you'll pay at least $699.

That's a lot to ask, especially for someone who wants the newest model every year. You can help soften the blow by trading in an old model. Apple's trade-in program will give me $225 for my aluminum Series 3 with GPS and Cellular that I bought last year, but that's less than half of what I paid for it.

Also, the Apple Watch doesn't work with Android. That's not a terribly big deal, but my wife doesn't use an iPhone and I really wish I could get her an Apple Watch so we could compete on workouts.