Upgrading from any prior version of Drupal to Drupal 8 will cause serious sense of humour failures amongst everyone involved. Guaranteed. While the core Drupal development team are somewhat better than they were there's still an unpleasant ivory-tower syndrome there and if you can't mind read and predict the future then whatever you build, or have built, will not be easy to update. The more plain, vanilla your installation the easier it will be upgrade but for many situations I'd honestly consider just recreating the site than attempting an upgrade.
It's not that Drupal 8 isn't heading in the right direction, it's been steadily lagging more and more behind other CMSs such as wordpress when it comes to backend usability and ease of use but IMHO there's still a very long way to go. The underlying changes in Drupal 8 will make this transition rather easier and hopefully swifter.
Biting the hand that feeds IT
