Yes, you should apply this update.
WordPress releases major core updates (ie. 4.4.x to 4.5.x) regularly, about 2-3 times each year. In between these they will also release minor updates (ie. 4.4.1 to 4.4.2). The major updates typically introduce new functionality, enhance current functionality, and address non-critical bugs. The minor updates typically address critical bugs and address security concerns.
It's important to keep your core installation updated as often as possible in order to ensure your site is patched against the latest known security issues.
Typically, updating WordPress core only causes issues if/when your active theme or plugins have a conflict with the changes in the latest version. It's important to keep all themes/plugins updated to the latest available version to avoid these conflicts but also to ensure that these are also patched against the latest known security issues. Also, keeping these updated helps avoid conflicts.
Keeping your site updated is so important, there is an entire industry built around making this easier or outright doing it for you.