I don't really agree with that at all. I read most of the manga after it's already aired to see the differences, and I find the manga to be paced almost TOO fast. Especially in this arc. The amount of crap that goes on in any given chapter makes the whole thing seem like a frantic clusterfuck.
And, at the end of the day, fights just fucking suck when they aren't animated.
Things like Whitebeard tipping the entire island are about 10x cooler in the anime than they come across in the manga.