The former Watford boss, who left Vicarage Road 10 months ago, has been confirmed as successor to Paul Lambert after he quit to take over at Norwich.
"It's a progressive club that wants to go forward. The ground is fantastic, it feels like a new project and everything is set up," said Boothroyd.
"I've seen the squad. They can score some goals as we've seen and it has a really nice balance to it. I've not been this excited in a long time.
"No-one has bigger expectations than me. I'm confident, I'm excited and I'm really looking forward to it. We'll get this place bouncing again."
Boothroyd also confirmed caretaker boss Joe Dunne will remain on the first-team coaching staff, adding: "He's going to be very important to us. He's a Colchester man and I need that."