The Direct connect protocol suffers from high bandwidth usage, unusual requirements for parsing, lacklustre internationalization support, and parts that seem to have been crafted to overcome network handling bugs in older versions of Microsoft Visual Basic (which NMDC was developed in). The protocol does not try to hide the identities of the peers, nor is it very optimized for swarm-downloading such as BitTorrent since it lacks partial file-sharing and (in many clients) segmented or multisource downloading.
Continued interest exists in features such as ratings and language packs. However, the authors of DC++ have been actively working on a complete replacement of the Direct connect protocol called ADC, designed to address the former's weaknesses.
One example of an added feature is Tiger-Tree Hashing of shared files (TTH). The advantages of this include verifying that a file is downloaded correctly, and the ability to find files independent of their names.