Do you like shounen battle mangas in the vein of Naruto? Then you'll probably love this, it has all the trademarks of the genre. From loud obnoxious kids who "call out" their super attacks, to enemies who becomes friends, friendship Über Alles, lots of (meh) humor, puppy romances, mild fan service and so on. Plus the art is amazing, and it's all in color. Really, the art is as close to 10/10 as it gets, even if it's not exactly to my own taste, it's nonetheless great.
Imo, Douluo Dalu is one of the (very few) good novels in the reincarnation/transported to another world genre that's flooded the market the last couple of years. That's thanks to good writing, characters with believable motives, an above average world-building and magic system, on top of that, it's also quite dark and serious at time. Especially when you compare to the Japanese "light novels" in the same genre, with their worthless, spineless, looser otakus as MC.
The manga is everything the novel is not, in a bad way. It's feels like a completely different story, with the same characters in the same world, told by a different author with a completely different demographic in mind. Personally, I hate it when clumsy directors/editors tries to make something original of a scripts based on book (or animes based on mangas for that matter). Some succeed of course, and turn a good story into something amazing, but the majority just fail horribly due to them lacking the talent that the original author had. A good example of this is Kurokami, which also was butchered and watered down for a different demographics.
Basically, the author took pretty much every single (interesting) adult element of the novel and turned it into a god damn childish battle manga, devoid of any depth whatsoever. Let censor the gruesome deaths, sex, prostitution, torture, slavery, psychological traumas etc, and lets turn it into something completely different. I know, why not add some idol elements, school life and slice of life moe BS to the mix, you know, to really set it apart from the novel? Done, done and done! What you end up with, is a watered down, cliched shounen battle manga instead of a interesting fantasy story. Then again, pretty much the whole anime & manga industry have gone down the road of epic fail the last 5-10 years or so.
I'll give it a 4/10, and that 4 is due to the amazing art.