"Talking about Tim Cahill, he's going to be great," Henry said. "We're going to have to wait for him to undergo his medical.
"He's going to be a great asset for us and also for the league.
"If you saw the guy play the way he plays, I love the commitment and I always loved his commitment. He's great in the box, his headers are unbelievable. He fights back to the net and his football brain is great also. Hopefully that can be a plus for us."
Norwegian midfielder Solli, who posted a welcome note on Twitter before having to delete it, was also looking forward to Cahill joining him at Red Bull Arena.
"I actually played him when we got our ass beaten, beaten pretty hard against Everton when I was in Brann, when we played the European cup," Solli told the NY Post.
"I've already been playing against him and he's a phenomenal player.
"I was wishing a great player (welcome). I'm pretty sure he's a good guy too. I'm sure it will be very interesting to see if he arrives. I'm looking forward to it."