I've had the Nike watch since October. My original had a problem downloading to the computer after a few months and I just received a replacement under warrentee. From what I've seen, having a failure this early isn't typical.
The distance measured seems reasonable. On a measured straight rail trail that I run regularly, it's reliably pretty close to dead on. I did a long paced workout on the track last weekend and it over measured the distance by about 2%. I think that's typical for GPS watches.
There are a few things about the watch that detract from its use. It displays a "main parameter" which can only be changed from the configuration utility when the watch is attached to a computer, you can't change this on the watch by itself. Likewise if you want to set up an interval routine this can only be done with a computer. The "second parameter" field is selected via a rocker button on the side of the watch that scrolls through the list. The configuration utility lets you choose what items are on the list.
The backlight is activated by slapping the watch, that is, there is an accelerometer in the watch so you're not actually pushing a button. The up side of this is that it's easy to do if you're wearing gloves or some such. If the watch is in a manual split mode, the same mechanism is used to record split times. The down side here is that you can't see the watch in the dark without recording a split which can be frustrating. It's also possible to accidentally record a split if you jar the watch and there is no user accessible sensitivity adjustment.
The biggest issue with the watch is that the only utility available to off load and analyze data recorded by the watch is the NikePlus web site. The impression I get of the web site is that it is designed by a bunch of graphic artists who have no interest in presenting any meaningful data. So when the painfully slow flash crap finally loads you're presented, for instance, with a animated runner leaving behind a "smoothed" time versus pace graph that seemingly has little to do with the workout that was run. They also didn't bother to label the axis, so even if the curve fit weren't bogus you still wouldn't be able to figure out your pace at any particular point in the run. The heartrate graph, at least, has sliders that allow you to measure points, but the resolution is poor. Finally you can get a plot of your route on a map which works well enough, but I usually already know where I went.
I don't have any hands-on experience with Garmin Connect, or whatever their toolset is called, but it can't possibly be as bad as Nike's. For that reason alone I'd steer you to the Garmin product.