Yes, Arlo is a puppet that hosts a YouTube channel. And yes, he is just about as clean and family friendly as you'd expect... for the most part. In the end, this works in his favor, as Arlo talks about Nintendo related content roughly 99% of the time, whether it be news, reviews, or speculative/retrospective opinion pieces.
Arlo also chimes in on other companies from time to time, and does reviews and live reactions as well. He's spoken in defense of Super Mario Sunshine, reviewed plenty of games, from Yooka-Laylee to Resident Evil 7, and had plenty to say about the Switch -- all while talking through his fuzzy blue puppet.
Sure, the puppet idea is a gimmick, but it's a good gimmick; Arlo's look and feel would be very difficult to mistake for pretty much anybody else. Plus, you always know what you're getting into with him, and if he ever changes things up in terms of appropriateness, he makes sure to let you know right away.
His family friendly nature doesn't stop him from being negative, mind you, as Arlo never sugarcoats his opinion on anything. He was among the first to deride the first trailer for Paper Mario: Color Splash and was bluntly honest in his review of Star Fox Zero.
Arlo has some quality videos, some interesting discussion topics, and an appealing puppet face greatly articulating it all. Give him a look.