Very large data-sets (e.g., global roads at ~200MB) are very difficult to download at one go when in poor/unreliable bandwidth areas. Suggest one or more of the following:
1. breakup data sets into smaller regional and/or country level chunks
2. allow downloads to resume after interruption
3. use distributed methods of serving data (p2p, torrents, etc) ... this will also reduce your server / bandwidth requirements!