Just completed a fairly painless transition from SQL Server to MySQL. I used the very useful MSSQL2MySQL. No Triggers, Views or any other complicated stuff. In rewriting the SQL itself the only problems I had were with built in functions and the TOP command.
SQL Server to MySQL equivalent functions:
ISNULL => IFNULL (same syntax)
GETDATE => NOW (not CURDATE as that doesn't include the time)
SELECT TOP x => LIMIT x (at the end of the statement not after SELECT)
DATEADD => DATE_ADD