I am administrating my site, which was built by a developer using WordPress 4.4.2. Since I am just learning my way around WordPress, I am wary about the message on my dashboard:
WordPress 4.5.2 is available! Please update now.
Will doing this change the dashboard so much I will not be able to continue upgrading my site with the knowledge I have learned so far?
Yes, you should apply this update.
To elaborate:
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.
You can see timeline of WordPress releases and links to summaries of changes at WordPress versions page in Codex.
4.5 release came out only about four months after 4.4. It didn't contain any major changes to dashboard.
As far as I remember the last release with major dashboard overhaul was 3.8 back in 2013. It's infrequent occurrence due to amount of work it takes and even then there are usually enough similarities to not get lost. WordPress project is pretty conservative about long term changes.
