50% fill factor is low. It means that half of each page is empty which means your table will take twice the space it needs and queries will do twice the IOs that would otherwise be necessary.
Fill factor that low is very seldom necessary. Can you ask the DBA who suggested that why he goes for such a low fill factor?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability