[Galaxy S I9000 Q&A, Help & Troubleshooting] andrewluecke:
The big problem is that many of them seem to be testing quickly from their chair.. There is overwhelming evidence that the GPS doesn't work accurately, but barely any showing it does.. In fact, in one case, I saw someone claim the unit was working perfectly, but the track they showed was on a straight highway, and was fluctuating excessively between both sides of the highway. And the most vocal of those who claims it works perfectly don't seem to be posting logs..

There is also some confusion between whether it is "fitness grade" or "car grade". Car navigation GPS can snap to tracks, and has more room for accuracy errors, because it can assume you always exist on the closest road, and if you use directions, it can assume you took the correct turns when it told you to do so (and correct itself a bit later). That's what most car units seem to do, and it helps compensate for most inaccuracies. It can lead to a bit of pain though if you make lots of turns, some of which aren't correct. Some people are possibly happy because they have used dedicated car units before which suck (some navman's take at least 5 mins to get a basic lock, negating any benefits of having them), but, since some phones offer better directions apparently, people are complaining it should be better.

Fitness grade requires MUCH higher resolution to be usable, because the distance is shorter (generally), and if your GPS veers off course, it gives you a false indication of jogging distance. Garmin forerunners feel generally like they are within 1 or 2 meters a of the time (but occasionally veers off 3), but from what I've observed standing still, the flaws may be less visible when moving, but simply appear as slightly off course.

Then there are those people who stare at the SNR/locked satelites for hours at end without checking whether the long/lat is actually correct, or the accuracy boundary (they see 5m accuracy, but don't actually check if it is accurate within 5 meters). I was one of these, until I realised that the accuracy boundary was wrong..

Part of the issue also comes down to firmware though. People are using pre-release/leaked firmware (which might not even be complete) and are judging the GPS quality based on that. No comment needed except, don't assume that Samsung aren't working on fixes because there is no fix in pre-release firmware.

I haven't properly tested either though personally because I use a forerunner for jogging (waterproof), and since I fly, I prefer to use maps to understand locations better. I did notice though that leaving my phone on my desk for a long period of time sometimes allowed the signal accuracy boundary to not include me (ie, allow a position of 20m away from me, but show 5m accuracy) intermittently. And this might explain the fluctuations in position many others have gotten..

Either way, it is debatable. The biggest issue is that the assumption so far is that everyone got exactly the same hardware, and exactly the same revisions. But the other problem, is that GPS quality is open to opinion, because in some areas, roads are so far spread out that even inaccurate GPS works fine for driving. It really depends on your needs. But the facts are, the accuracy of the GPS isn't worth debating anyway currently, because Samsung have already told us they are "optimising" the GPS in Sept, which may make this unit as good as a garmin forerunner anyway. All any of us can tell you as that we'll know the TRUE potential of the unit after the september patch.

But for me anyway, I think the GPS is fine (I don't need perfect accuracy, even if I needed this as a fallback in a plane)