According to Mark Sisson on his blog, acai berries are a great fruit but overly hyped up. He links to an article at A Friendly Skeptic which discusses any scientific research:

Here are some basic facts. The nutritional content of açai is 1-4 percent protein, 7-11 percent fats, 25 percent sugar, 0.05 percent calcium, 0.033 percent phosphorous, and 0.0009 percent iron. Açai also has small amounts of sulphur, vitamin B1 and E and beta carotene. It delivers 88 to 265 calories per 100 grams, depending on the source and preparation method.

A PubMed search for Euterpe oleracea reveals half a dozen relevant articles, but none clinical in nature. In fact, none has anything to say about its alleged health-promoting properties, except in the most general terms. Yes, it has antioxidants and antioxidants are good for you. But it is a far stretch to claim that this juice or its constituents will cure any disease.

Simply put, I can discover no scientific basis whatsoever for making medical or health promoting claims for açai.

According to Leslie Taylor, N.D.

"the fruit liquid "is not really that nutritious in comparison to many other fruit juices"

Paleo Friendly? Its paleo friendly rating would depend I think on it's sugar levels and glycemic index and load. I can't find any specific ratings of its GI on the web, though many websites for promoting acai claim it is extremely low. Until I see some hard numbers I will assume it is hype. While the fruit might be paleo compatible, limiting fruit intake and thus sugars would rule out using this food as a staple.