Has ANYONE had a Bad experience migrating to C5 from earlier versions?

Has ANYONE had a Bad experience migrating to C5 from earlier versions?

I have some large C4 apps and am looking at the upgrade as I am told the deluge framework in C5 is faster and will then allow me to use C5 features like the kanban report.
BUT I don't want to dive into other bugs or issues with C5 at this stage... anyone had any experience they are willing to share???