It really that some people just expect a lot out of them--most any of the GPS watches are going to be fine if you just want to track time, pace and distance.
And there are some technical issues some watches have that affect some users and not others. Like my Garmin 405--it has a touch bezel you use to switch between menus, modes, screens etc. that doesn't work if it or your fingers are wet with sweat.
Long story short, any of these GPS watches will be great for the average person who just wants to track pace and distance. But they have some quirks that may annoy people with more advance usages or who are pickier than me with their gadgets.
I've been looking at GPS watches for quite some time (probably around a year). Never pulled the trigger and use dcrainmaker exclusively for research. I ended up buying the Endomondo app for $5 and a SPI belt. Pre-injury, I only ran roads and always along mapped routes on dailymile (3, 4, 5, 6, 7 mile routers all around town leading from my driveway and would just do loops to hit the bigger marathon training distances). Anyways, you can set the Endomondo app to alert you to whenever you hit a specified distance. So, if I tell it to alert me every half mile, my phone will state "0.5 miles, 1 mile, 1.5 miles" when I hit those distances. This is such a good feature for me as I'm still recovering from surgery (15 weeks this week) and am only running on trails for the softer surfaces.
The biggest issue is carrying a phone while running and I am not going to wear an arm band. I googled and found the "SPI belt". I bought it for $20 and it hugs the body nicely. Doesn't really protrude and holds my S3 and car key perfectly. Not all my 5" shorts have a small pocket so I use the belt on those days. I only mention all of this to present an alternative to those looking at GPS watches. I'm unsure if the free endomondo app allows alerts like that (it's only $5 and use Endomondo app for cycling as well). The app also auto pauses if it detects that you're idle which is a nice feature IMO when you're waiting at a stop light or intersection. I've tried Strava and did not like how it doesn't auto pause and some of my longer bike rides ~20 miles, I would lose the GPS signal on the trail and it wouldn't tell me signal was lost and it NEVER picked it back up. This happened 1/3 of the time I used the Strava app (I cycle solely on trails) and it just isn't acceptable. I wanted to like Strava as their site's interface is great for friends and cycling.
Overall, I've been very happy with Endomondo for both running and cycling. The mileage is generally accurate and when exercising with others who also use Endomondo, their mileages have varied by only a tenth or two of a mile. I also subscribed to Endomondo premium ($15/year) but so far it hasn't been worth it. I really just wanted to support them and figured a few extra perks on the site would be handy. I really wish DailyMile had an android GPS app as it has a great community for runners but can't beat Endomondo's functionality and price point.