Doesn't mean he's Galactus caliber. Lemme put it this way:
Uatu the Watcher said that Galactus does not lie, and his word is his bong. Uatu has observed Galactus, so he knows these things.
If Galactus says that he is as powerful as he says he is, then it's so. He's not a liar, or a braggard by any way, shape, or form. People keep saying that there needs to be a showing of Galactus blowing up the universe ten times over, when he doesn't even enjoy being Galactus. Hell, he's regretful of the fact that he's a force of nature. Here's how he describes himself.
"I am he who is Galactus! I am he who is the power throughout a thousand thousand worlds! Mine is the will that is the word! Mine the hand that is the might! I am the then! I am the now! I am the yet to be! [...] I am him who is Galactus! My every whim is living law throughout a thousand thousand worlds! I shall regain my fallen herald! I will choose the time! I will choose the place! Then, I will choose... the strategem! And if Earth must die that I shall live... so shall it be! For, am I not... Galactus?!!"
- Silver Surfer trade paperback
* "Of all the creatures in the vastness of the universe, there is none like me. I was present at the birth of the universe, and I shall be there at its end. Though I ravage worlds to live, I bear no malice to any living thing. I simply do what I must to survive. And why must Galactus survive? For, no matter how many worlds I devour... How many civilizations I destroy... It is my destiny to one day give back to the universe — infinitely more than I have ever taken from it. So speaks Galactus!"
--Galactus, The Origin of Galactus
Yeah, he's not going to go blowing up universes for no reason. He doesn't need to show off his power by any means. There's no point if you don't enjoy what you are. When it comes down to Imperiex, there is no solid proof that he comes near Galactus. With that said, Asgard is taking this one 10/10 times against the Nipplehead Galactus Wannabe.