Sperm and embryo freezing is more of a common place then freezing unfertilized egg cells for two main reasons.  Sperm cells are about 180th the size of mature egg cells, which means that there is less water in a sperm cell then an egg cell.  With less water in a cell it is less likely to be damaged by ice formation (ice formation can lead to the cell rupturing).  Embryos are about the same size as egg cells but after being fertilized the cell has gone through a great deal of change and is able to deal with much more stress than regular egg cells.

However, there is an advanced egg freezing technique called cryogenic preservation, that first dehydrates the cell (eliminating the risk of damage to the cell because of ice formation).  They then uses a slow freezing and rapid thawing technique for the best results.

I have been doing some research online about egg freezing and based on what I have read, the success rates of egg freezing has gone up considerably since it first started and the data to date seems to suggest that the children born from frozen eggs are healthy.    In my travels I have found a company called Extend Fertility www.extendfertility.com.  Their website has an informative and empowering outlook of women and their choices when it comes to their reproductive health.