TOP 10 Episerver CMS 10 Changes for Developers

First of all, Episerver 10 is backward compatible 99.9% but in upgrade you should be aware of few things! Here is my top 10 list of CMS changes:
1 Add-ons EPiServer.CMS.Core All add-ons are not yet updated to support new major version.
2 CMS-2295 EPiServer.CMS.UI Remove support for legacy dot syntax for dojo modules
3 CMS-3812 EPiServer.CMS.Core Confusing handling of empty/null properties
4 CMS-1449 EPiServer.CMS.Core Date/time should be stored in UTC by default
5 CMS-4167 EPiServer.CMS.Core Change ContentCoreData StartPublish and StopPublish to DateTime?
6 CMS-1380 EPiServer.CMS.UI Move EPiServer.Shell from EPiServer.CMS.Core to EPiServer.CMS.UI.Core
7 CMS-4149 EPiServer.CMS.Core Remove support for legacy value types for PropertyData
8 CMS-4110 EPiServer.CMS.Core MovingContent and MovedContent isn't different when removing a content
9 CMS-3991 EPiServer.CMS.Core PermanentLinkMapper API is hard to understand/use
10 CMS-3290 EPiServer.CMS.Core Make LinkItem members virtual to simplify unit testing
Full list of release updates: http://world.episerver.com/releases/episerver---update-134/

Episerver ADD-ONS for v.10

Many Episerver add-ons seems to have dependency support for Episerver.CMS.Core version up to 9.999 or less than 10.0.0. So you need to temporarily remove those add-ons if you want to install the version 10. Probably those add-ons will be updated soon or at least most of them. This is the situation today 2016-10-24. Version 10 SUPPORTED add-ons already Version 10 NOT yet SUPPORTED add-ons
  • EPiServer Visitor Groups Criteria Pack
  • EPiServer GoogleAnalytics
  • EPiServer.Cms.AddOns.Blocks (Self-Optimizing Block)
  • EPiServer.VisitorGroupsCriteriaPack
  • SiteAttentionModule
  • EPiServer Find Client API
  • EPiServer.Optimizely
  • Mogul.SEO.Manager.Package
Also be aware that in the end of the update you should convert all the DateTimes to UTC time, but it's just running a simple command (PM> Convert-EPiDatabaseToUtc). utc I have my first Episerver 10 project in production already. The update went smoothly and it's up and running. If you don't have restriction from relations like add-ons or other NuGet packages, I would recommend you to update also!