How widespread is the adoption and usage of database snapshots?
Database snapshots are used in SQL Server 2005 or later every time you do a DBCC CHECKDB - so they are widely used, even if it is behind the scenes. Perhaps the biggest hindrance to adoption is that Management Studio didn't offer support.

It sounds like an ideal use of snapshots in a dev environment just for quick script deployments and quick roll backs. The only downsides, apart from no tools support, is to watch disk capacity where you put the snapshot file, and ensuring you don't have too many snapshot databases running on the server at the same time.