So many things, it's not even funny. But you already listed most of the pressing ones.
The uservoice site is filled with issues, too.
Offline data handling. Won't upload data unless you start with a connection, lose connection, regain connection. The client also crashes, and consequently loses whatever buffer existed, if you lose connection for more than half an hour or so. But there is also a window between crashing and successfully uploading/connecting once you regain an Internet connection. After too many unsuccessful reconnect attempts it either permanently gives up purposely or due to bugs. If it hasn't crashed. This should be fixed. This should also be changed so you have a persistent buffer limited only by disk space. An initial data connection should not be required. You should be able to go record roads without Internet access for weeks or months at a time, get home on wifi, and upload the 50+ GB of data that consumed all the space on your 64 GB iPhone 4S. And then head back out and do it again. But you can't. You need cellular Internet the whole time, more or less. So mapping remote areas, or doing so simply while avoiding using cell data, is impossible.
www vs. world regarding forums is a bit annoying. Emails for subscribed topics contain links don't work from the 'other' domain. You need to manually change one to the other. Completely unnecessary. I don't know if you actually need both domains for other things or not, but for the forums this should be taken care of by getting rid of world.
Cookie issues preventing staying logged in "fixed" by removing the "stay logged in" check box? How hard can it be to fix a "stay logged in" issue? Every other website on the planet seemed to easily avoid that problem.
And more I'm forgetting since I'm so tired at the moment.