[Tested Gaia GPS v9.0 on iPad 2 and iPad 4]
First of all, kudos to the new Gaia GPS version! The interface feels much more polished and faster than the previous version. I really like it! Nevertheless I have a few remarks:
* Initially I liked how the new version displays maps much sharper on Retina displays (iPad 4 vs iPad 2 in my case). However, out in the field this actually turned out to be a disadvantage: Labels like place names, street names, height lines, river names,... are so small on the Retina display, they become almost impossible to read. Because most map sources are still tile-based and all devices get the same tiles, the Retina iPad displays everything twice as small at the same zoom level! Zooming in doesn't help because then it displays the next zoom level... twice as small. Only when zooming in further than the maximum zoom level things finally get bigger.
I assume it's not practical to offer map sources rendered at different DPI settings for all various screen configurations. So can we please have an option on the "Settings" screen to display maps twice as big even if that kind of ruins the advantage of a Retina display?
* I like how you can enable and disable layers on the "More Layers" screen to keep the "Layers" menu clean with only relevant maps. However, I'm unable to remove the "US Topo (CalTopo, USGS)" layer. It's not shown on the "More Layers" screen and swiping left does not give a "Delete" option. This layer has absolutely no value on this side of the pond. I'm also unable to get rid of the "World Imagery (MapQuest)" layer. I can remove it, but it returns automatically on the next application launch.
* What happened to the OpenCycleMap / Cycling Topo map source (also called "World Topo" by Thunder Forest in the previous version)? I can still see and use it from my layers menu but it is not listed on the "More Layers" screen. I'm a bit worried what happens if I would happen to delete it from my layers menu.
* I'm not really using the areal/satellite imagery map sources, but I noticed that "World Imagery" by Google doesn't work properly. Beyond zoom level 12 it suddenly turns into regular road map. "World Imagery" by ESRI or "Imagery + Roads" by Google work just fine, though.
* What exactly defines the icon that is shown for the various map sources (areal/satellite, road map, topo)? Map "OpenLandScapeMap (topo)" for example does have the icon of a road map while it's clearly a topographic map while "HikeBike.de" is shown as topo while it doesn't provide any topographic details.
* If you work in offline mode with downloaded maps and are zoomed in beyond the maximum downloaded zoom level (mainly to see things bigger on the Retina screen) and then move around the map, the areas that are outside the initial view do not get displayed at their maximum (downloaded) zoom level but completely blurry at a much lower level. You then have to zoom out to a zoom level equal to or lower than the maximum downloaded one for the screen to redraw correctly.
* When on the screen where you can select the area to download for offline use, there's a rounding bug in the size displayed in the top right corner. Once the area is over 999 MB (accuracy up to one megabyte), the size is rounded to gigabytes (997, 998, 999, 1.0, 1.0 ... 1.0, 2.0).
* The zoom level and size labels on download map screen do not always reflect the actual zoom level used for downloading. If you do not tap exactly on the slider "button" but slightly right or left from it, the button moves but the zoom level and size labels do not update. It's even possible to move the slider all the way to the left while the labels still indicate maximum zoom level 18. The download will be using the zoom level of the slider - not what is displayed in the labels.
* On the same screen (download map for offline use): If you select an area and press "Save" you are asked for a file name. It is however impossible to cancel that dialog.
* The white arrow in the blue button to fold out or collapse the "Trip/Saved/Settings" panel is pointing in the wrong direction after rotating the screen with the panel expanded.
* Tapping "Last Sync" on the "Settings" panel performs a new sync operation. However if "Sync/Backup" is disabled it still performs the sync. That sounds a bit illogical but personally I don't mind it. Worse is that doing so silently switches on "Sync/Backup" without being visible to the user. It's not until switching to another screen and then returning to the "Settings" page the change is visible.