Read the What's new for V8i'. If you see a new widget you can't live without then yes it is worth the effort to upgrade to the current release of InRoads V8i.
With that said I would suggest you read the Whats new for the next release of V8i. The upgrades to MicroStation looks worthwhile all by themselvs. The enhancements to InRoads will be fantastic or fatal depending on how my users react to the changes. I hear the next version should be out the end of the year. I hope to upgrade to it in March(?). The enhancements will give the designer a great deal more power. Fun, fun!!