The first thing we noticed: This is a very big watch—the largest sports watch we’ve seen. However, the watch is quite light and during our test runs I found that the size of the Ironman Global Trainer GPS was not really a nuisance at all and fit well.

The watch is intuitive and easy to use right out of the box, with all of the basic functions easy to access before even reading the manual. That ease of use was slightly better than the Garmin GPS watches we’ve tested, but fell short of Nike’s SportWatch GPS by TomTom.

Unlike some Garmin touch-screen and touch-bezel watches, which can be difficult to manipulate on the fly, the Timex is controlled by simple, standard buttons. It has a nice four-field screen so you can simultaneously watch several different bits of data, like pace, elapsed time, lap time, and overall distance. However, the font Timex uses for its numbers is not as bold or high contrast as the font Garmin uses, so it’s not as easy to see the numbers at a quick glance.

For interval workouts, the Timex was fantastic—splits were very easy to capture and view. The unit comes with good online workout analysis tools (Training Peaks). The heart rate strap fit snugly and the feedback was consistent. The battery life is better than average (15hrs of GPS mode) but not the best (the Garmin 310 XT lasts 20 hours in GPS mode). At 2.96 ounces, it’s just a smidgen heavier than Garmin’s 310 XT (which is 2.5 ounces).

In our accuracy test (5,000 meters on the track), the Ironman Global Trainer GPS was a hair more accurate than any other GPS watch we tried—just 28 meters shy of 5,000 meters, which is quite accurate. The pace tracker seemed consistently on target, and responds rapidly to changes in our speed.

The main disadvantage of the Ironman Global Trainer GPS is its face size – it’s simply too big for smaller wrists and some female runners.

The watch does not have the capability to track open water swimming distance, the way Garmin’s 310 XT does, a disadvantage for triathletes who train outdoors. Additionally, the Timex “Virtual Partner mode”—where you race against an imaginary pacer on the watch—is not as sophisticated as a similar function on Garmin watches in that you set your distance and time but are unable to alter it if you choose to do so mid run.

Treadmill runners: The Ironman Global Trainer GPS also does not have the ability to support ANT + foot pod like the Garmin, which is useful for tracking indoor running.

Since the Timex Ironman Global Trainer GPS launched in September 2010, the price has fallen from $360 to $300, which makes it a more compelling value compared with Garmin’s highest end watches.