The main feature in Emule which I would love to see in Limewire is when you right click the taskbar icon you get a menu that lets you change the current Upload/Download rates. This is very useful, far better than the current one in Limewire, which doesn't even let me set an upload rate of between 5kbps and 11kbps which is best for me as an ADSL user who wants to be able to surf at the same time.
The current method is very irritating and doesn't let you accurately or easily set the limits.
Emule also has an excellent statistics feature (not critical), the ability to download files by copying in the Key String.
It is also possible to list what people you are downloading the file from, unlike in Limewire.
There should also be a download archive thing added for zip and rar files. Currently it is under "programs", which isn't really right.