This thing is the bomb! I've had mine for almost two months and I absolutely love it. I only have a few minor gripes about it but nothing major enough to reduce the ranking. Positives: 1) Overall good tracking, this depends a lot on the user and how patient he/she can be while waiting for a good satellite lock. The less you move around while it's searching, the better. 2) Options galore to track your training progress and evaluate your workout. I would recommend signing up with motionbased.com and using their free service; they have a more detailed workout summary than the software that comes in the box. For a fee you can get even more details, but I have not tried this. 3) Wireless HR monitor seems to be very accurate and is a great addition to help with training.
Negatives: Few and minor 1) As with any GPS unit, the 305 will not track as well in dense foliage, on cloudy days, or if you move around a lot while it's trying to get a satellite lock; this is to be expected. 2) Its too bad the technology isn't developed enough yet so that they could make these things a little smaller. It would be great to wear it when not working out, but it is simply too huge. 3) The elevation tracking is not super accurate. I'm told that this is pretty much always the case when altitude is measured by GPS and not barometric pressure (like Suunto does). The readings I've seen are always in the ballpark, but I'll usually have spikes and drops of +/- 200ft even when I run on a level track. Again, I don't think this is unusual for a GPS of this size.
Overall, I would recommend this to anyone who wants to track their progress when training and analyze their workouts. It has yet to disappoint me.
I purchased this watch/"GPS" a few weeks ago and I must admit, I'm pretty disappointed. I intended to use it to track routes and keep up with my training (trail run, bike, paddle, etc.) but it turns out that this is probably not what this device is best suited for. It seems that it would be best used strictly as a traditional GPS unit to track routes while hiking/camping. I would however highly recommend the Garmin Forerunner 305 (see my review for it) for anyone wanting a good (not perfect) GPS unit to track progress while training. Overall the X9i only gets 2 stars from me mainly because 1) It is not intuitive (included instructions help some, but keep them close at hand), 2) The distance it recorded for my run was way off (I ran approx 4.5 miles; it recorded 7.75) and 3) It is gigantic (I understand this is necessary to cram all of the circuitry needed for GPS) Bottom line: If you want a compact GPS training device, go with the Forerunner 205 or 305. If you want a GPS for hiking/camping buy a real GPS. Sure, it won't be quite as small, but it will work much better.