Same as with the GW52, the logit thread is much too long to find useful info.
But this is much harder to be definitive, because of phone variability.
Although the app is fantastic, giving all our 6 divisions readable on the water as well as speed talk telling you how fast your going in close to real time, (there does appear to be a slight delay), with "last run" telling you the results of whatever division you've selected in "zoom" view.

The biggest problem I've found is the display turning off, this causes both the pixie3 and Xperia E1 to go crazy, missing chunks of data, and sometimes giving as much as twice actual speed. Although logit has a "screen on" button, this only affects the normal time out after non use switch off. Any inadvertent activation of the phone controls can turn the display off. I've resorted to using a fereo roche chocolate box lid to protect the phone face from being touched, and this works well most of the time.

There's also the problem with all the different phones, there appears to be two resolutions that phones come with, a coarse one just under 0.5 knots and a better fine one just under 0.012knots. There is a list being compiled on the "logit resolution" thread.

But resolution doesn't seem to be the major factor in accuracy, that I think is down to satellite sensitivity in some way. Unfortunately the number of Satellites shown isn't a reliable indicator of this, and it's hard to define.

I've only been testing the Sony Xperia E1 and the Alcatel Pixie3. and both of these have poor satellite sensitivity, they both need a very clear view of the sky, although the xperia reports more satellites than the pixie, I get better results with the pixie than I do with the xperia. And wearing them on my head gives better results than on my arm.

Then there's the matter of headphones and armbands, I'm still trying to find an ideal solution that's not too expensive, at the moment waterproof pouch and earphones are about 3 times the price of the Pixie3

So at the moment, things are still a bit grey, certainly it's recommended to use a recognised GPS for recording and the phone as a guide.