If you are going to send alot of data try using XML objects as instead
Datasets are very verbose e.g they contain a lot of data about schema, datatypes, relations, constraints e.t.c.
XML objects outperfom Datasets where large amounts of data are involved. The only downside to XML objects is that they involve a lot more coding.
Also the transmission of datasets exposes dataset schema to hackers especially where no encryption is used.
for my web services i try and avoid transmitting Datasets whenever possible