uTorrent is a small and incredibly popular BitTorrent client.
Micro-Sized Yet Feature Filled
Most of the features present in other BitTorrent clients are present in uTorrent, including bandwidth prioritization, scheduling, RSS auto-downloading and Mainline DHT (compatible with BitComet). Additionally, uTorrent supports the Protocol Encryption joint specification (compatible with Azureus 126.96.36.199 and above, BitComet 0.63 and above) and peer exchange.
uTorrent was written with efficiency in mind. Unlike many torrent clients, it does not hog valuable system resources - typically using less than 6MB of memory, allowing you to use the computer as if it weren't there at all. Additionally, the program itself is contained within a single executable less than 1 MB in size.
Skinnable and Localized
Various icon, toolbar graphic and status icon replacements are available, and creating your own is very simple. uTorrent also has support for localization, and with a language file present, will automatically switch to your system language. If your language isn't available, you can easily add your own, or edit other existing translations to improve them!
Actively Developed and Improved
The developer puts in a lot of time working on features and making things more user-friendly. Releases only come out when they're ready, with no schedule pressures, so the few bugs that appear are quickly addressed and fixed.