The Good: The Garmin Forerunner 225 has an always-on display, accurate GPS for tracking runs, a wrist-based heart-rate monitor, and can track steps and calories. It's water-resistant and can be worn in the shower and pool. The Bad: Heart-rate tracking is limited to workouts, there's no automatic syncing, sleep data lacks detailed information, and Garmin's mobile app is dated. The Bottom Line: Runners interested in tracking both heart-rate and all-day activities can't go wrong with the Forerunner 225. Editors' note, April 15, 2016: The Garmin Forerunner 225 has been replaced by the Forerunner 235. Read our full review here.Over the past year, an influx of dedicated fitness gadgets have included both GPS and heart-rate sensors. The and Fitbit Surge may come to mind.Until now, Garmin's stayed out of the wrist-worn heart rate territory -- the company's previous watches required pairing a separate chest strap to track heart rate. The $300 (\u00a3240, AU$389) Garmin Forerunner 225 changes that once and for all. This watch is Garmin's first to include a wrist-based heart-rate sensor, but that's not all.This is a runner's watch. It has both built-in GPS for pace and distance tracking, as well as all-day activity tracking. I've been hesitant to embrace these wrist-based heart-rate sensors, assuming they would lack accuracy, but the Forerunner 225 has helped change my mind. It's also one of my favorite running watches from a design standpoint, falling just behind .The Forerunner 225 adds a lot of new features to a great running watch. It's the running watch I would personally buy. Is it perfect? No, but this comes closest to meeting my needs. What it doesThe Forerunner 225 is an all-day activity tracker, running watch with GPS, and heart-rate monitor all wrapped up into a single device. The GPS is used to accurately measure pace and distance when running outdoors. Thanks to the optical heart-rate sensor on the back of the watch, you can track beats per minute both during workouts, and whenever you'd like to start measuring it during the day. The advantage of optical wrist-based heart rate monitoring is you get to skip wearing a chest strap monitor. The drawback, in many cases, is that wrist-based monitoring ends up being less accurate. This Garmin's optical heart rate measurements were a lot better than most.This Garmin watch also has an accelerometer for tracking all-day activities. It can measure steps, distance traveled and calories burned. It can also automatically measure your sleep at night, but it doesn't provide detailed information on sleep cycles or how long it took for you to fall asleepThe accelerometer also handles indoor distance tracking when GPS isn't available. It works, but isn't as accurate as using GPS. When compared to the treadmill's distance measurements, I found indoor runs to be off by around 0.05 to 0.10 mile.The Forerunner 225 also has inactivity alerts that will remind you to get up and move after an extended period of inactivity, as well as a vibrating alarm. The Forerunner is a nice everyday wristwatch, too. The only thing it's missing are smartphone notifications, like those found on the or Apple Watch. DesignIn the past, I have argued that most GPS running watches wouldn't be comfortable enough to be worn throughout the day. They tend to be big eyesores. While the Forerunner 225 is big and bulky, in a certain light it can be somewhat beautiful -- at least on a man's wrist, as the watch measures 48mm across. For comparison, the largest model is only 42mm. It has about the size and thickness of a Casio G-Shock. It's also only available in a single color: black with red accents.It's nice not having to take the watch off when I take a shower or go for a swim. The Forerunner 225 carries a water resistance rating of 5 ATM, which means it can withstand pressure of up to 50 meters. (You can learn more about water resistance ratings in watches and activity trackers here.)I also like the watch's color display. It's always on, so there's no need to tap the screen or flick your wrist to view the time and date. You won't have an issue reading it outside, even when in direct sunlight. Indoors or in low-light situations it could be a bit dull, but there's a backlight. The watch held up well over the course of my testing. I ran with it more than a dozen times in situations ranging from extreme heat to torrential downpour. There were even a few times I accidentally hit the face of the watch against the wall. It held up well until I tripped and fell on a recent run. There is now a small scratch on the screen. Clumsy runners, beware.Heart-rate monitor: Continuous and accurate during workoutsGarmin partnered with Mio to provide the optical heart-rate sensor on the Forerunner 225. The technique it uses is similar to what is found in the Fitbit Surge and Apple Watch. A flickering LED green light is used to light the capillaries, which allows the sensor on the back of the watch to measure the blood as it flows by.The process to acquire my heart rate was nice and quick, although times will vary depending on the temperature. In colder weather these optical sensors can have a more difficult time locking onto your heart rate. In order to test the accuracy of the heart-rate sensor, I ran with both the Forerunner 225 and a Polar H7 Bluetooth chest strap for a little over 20 minutes. I then compared the data that was recorded on both devices. Using the chest strap as an accepted baseline, I found the Forerunner 225 to be incredibly accurate. The watch measured my average beats per minute at 174 and maximum heart rate at 203 bpm. These results were only a single beat off from the chest strap, which measured me at an average of 175 bpm and a maximum heart rate of 204 bpm. You can view the full data from my workout below.