There are three types of updates, two or which overlap somewhat. App updates are through Google play store, and install updates to installed apps. Firmware, or system updates are through Samsung or your carrier (for carrier tablets), and security updates through Samsung.
All of those are optional, and present potential problems (app breaking, slower performance, new features that cannot be disabled, total device failure, I.e. won't boot) but solutions are generally available within days, and 99.99% of updates are without serious consequences!
I install all updates. If there is a serious problem, I just solve it by looking online. The firmware and security updates are a really good idea from a security standpoint, although sometimes the security benefits are hyped to prompt upgrades from obsolete devices.
I personally don't worry about firmware security flaws, because, compared to the total number of android users, only a miniscule fraction fall prey to exploits. If you're a high-value target, like an investigative journalist or political dissident, you must be more careful.
But for the average user you stand a much greater risk from unwittingly installing malware than from not upgrading right away.
Most malware apps are aimed at users who deploy their devices for nonprofessional uses such as social networking, photo processing, chat, games, UI customization, I.e. wallpaper packs!
Before you install anything on Android, make sure you know what it is, how many installs it has, feedback rating, and don't install anything you don't need. I hope this helps.