Keeping your Spree installation up-to-date is essential to keep it safe and secure. Each Spree version brings new features, enhancements and bug fixes so it's greatly beneficial for you and your clients to upgrade frequently.
The upgrade process is fairly easy and well described. Of course, it all boils down to the level of customizations and the way you've customized your Spree applications.
We strongly advise upgrading Spree incrementally, rather than in one big go.
If you're stuck and would want to get some professional help, you can contact us directly and request a quote for our consulting services.