Should I Upgrade My PHP to 7.2?

According to my ISP (GoDaddy), I am currently on PHP 5.6, and it's offering me PHP 7.0, 7.1 and 7.2 as upgrade options. Since I don't know anything about PHP, I need to know, is there any reason I should not upgrade to the latest version?

What version of WordPress were you using?

4.9.8

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What Theme and what theme version were you using?

Deja Vu 2.8.6 (is this the latest, or have I fallen behind?)

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