Filename Masking-
Imesh has a great feature that prevents your isp from spying on what filetypes your downloading. When files are transferred from one computer to another they are given a temporary, arbitrary name like file03543.dat and renamed on the downloading end upon completion of the transfer. This gets around problems with download filters and ISPs that will cut you off for downloading mp3s.

File Descriptions-
Imesh also includes a description field viewable during a search which gives info like bitrate, filetype, artists, tiltle and a short description. This sort of info is very useful for people who want higher quality(bitrate) mp3s and video.

Search and Sort Options-
Most importantly FILESIZE. Searching for video one finds alot of clips if one can't specify minimum filesize.
Another important one, BITRATE
Lastly FILETYPE/EXTENSION

Other than the need for these things, limeware is one of the best sharing clients I've used. It is quite fast and the swarm feature is great! The Gnutella network is great for finding hard to find files that the Imesh network doesn't have or won't reveal due to limited searches.