We have been using isql and sqlcmd (recently) for the past 8 years to deploy stored procedures, triggers, functions, views, scripts to our customers and recently to our QA team.

In our release script (or batch files), we will pass in information like server, database, userid and password. In addition, we also use this script to verify the release before applying so that we will not accidentally overwrite the database.

We even go to the stage whereby we have different customers running different SQL Server version and hence will need to use either isql or sqlcmd.