I like how simple it is, but also that you can have multiple versions of documents with different permissions level so people don't always need access all files at once! Sometimes there's some lag when saving or loading large amounts from one file into other (eg using an XML document).
Also sometimes if your PC goes idle while waiting in queue then computer freezes up - not sure why this happens as its fairly new program though could maybe just do something about performance settings? A very easy way around getting permission denied errors whilst uploading/downloading lots within same account would help alot too otherwise great product!! Having separate accounts per project saves time by avoiding having 2 logins etc which makes life easier especially now we are working remotely more often than ever before meaning less hassle logging onto computers etc.