A dash cam is a worthwhile investment, and could end up saving you a lot of money in insurance premiums. The key feature to look out for is Wi-Fi connection, this makes it so much easier to view, download and share footage.
Note there are dash cams with screens, and models without. Dash cams with screens are easier to set up and view footage on, but ones without screens are a lot less intrusive.
Both are useful, but we'd choose one with a screen for occasional recording (track days and scenic drives), but one without a screen setup and forget about for everyday driving.