Fixed Rate Loans

Security - Fixed loans allow a borrower to lock in an interest rate for a particular period of time (anywhere from 1-12 years).
Assurance - Knowing that your repayments are fixed for a set period no matter what interest rates do
Flexibility - You could also split your loan between a fixed portion and a variable portion.
Fixed has more restrictions (e.g. most fixed rate loans limit or do not allow extra repayments, or you cannot pay out the loan during the fixed period without incurring large penalties). Splitting your loan into two portions (fixed and variable) can be a good way to "hedge your bets" on interest rate movements. The fixed portion is locked in, whether interest rates move up or down. The variable portion moves with interest rates which is good if interest rates drop, as you get the benefit of less interest. You can split into thirds, quarters or more - sometimes there is a minimum amount required per portion. You should also consider any fees incurred in establishing multiple splits.
Features - Features such as Redraw or Offset are usually not allowed during the fixed period of a loan, however combining a Fixed loan and a Variable loan allows you to take advantage of features available on variable rate loans