This release has a few bug fixes, and some changes to modernise the export options, particularly with Cordova. Some features have removed because they are either no longer supported or are deprecated and will be removed in future. For example support for turning off WKWebView in iOS exports has been removed, since the alternative (UIWebView) will be removed in a future version of iOS. Similarly support for Android 4.x exports using Crosswalk has been removed as it is now unsupported and unmaintained; it also produced bloated APKs, and the vast majority of Android devices don't actually need it anyway.
There has been a bit of confusion lately over the new requirement in the Google Play store to support Android 8.0 (Oreo - API level 26+). Construct 2 has supported this since r256 (released in March) - you don't have to do anything. Note there are two versions specified for APKs: the minimum version supported, and the target version, which is basically the newest version the app knows about. The restriction for supporting Android 8.0 applies only to the target version, which C2 sets automatically. The version list when exporting sets the minimum version, which unless you have a specific reason, can just be Android 5.0 to reach most devices. You don't need to set the minimum version to Android 8.0 - doing so will mean you only support the ~15% of Android devices that have upgraded to Oreo so far.