note: I didn't read the LN, but apparently it's more mature and better explained - dropped at 36 chapters
So "Douluo Dalu", or for people who actually want to understand, "Soul land"/"Combat continent" is a manhua that at first looks really promising, but then goes ahead and does everything wrong.
Story: The story follows Tang San, a guy who was a prodigy martial artist of the Tang Sect of Hidden Weapons (so he was basically a ninja), who jumps of Hell's Peak to kill himself. After that, he is reincarnated in the "soul land", but he kept his memories of his previous life. Ths is of course a wonderful idea to create an OP character, because he still remembers all his ninja-techniques, which he begins to train again at the ripe age of 3 years ._.
After this, the author starts turning "soul land" into an RPG-world. Everybody in "soul land" can transform their soul into a unique tool called "spirit essence" (eg. a knife, a hammer, but also ridiculous things like carrots. Physical transformation into a beast is also possible).
All 6 year olds are tested to see what their "spirit essence" is, and the level at which they can control it (max = level 10). Of course, the MC has level 10 control, although he has a "junk spirit", which is grass. After that, he reveals to his father that he has a 2nd spirit, a hammer (which is an OP weapon + the fact that he has 2 makes him even more OP). After this his father disappears, but later it is revealed that he (spoiler) is one of the strongest people on the continent (end of spoiler).
Because he's lv 10, he's sent to an academy to train, which is also where he meets his love interest Xiao Wu (with whom he becomes sworn siblings, because that's not done before *cough*OnePiece*cough*) and his first master (the Grandmaster), who helps him to make his grass useful by using poison. How to train spirits? Well, kill a monster and absorb his soul. That totally doesn't look like gaining exp in games. There's even a power level system from 0 to 100.
After a few years in the academy, Tang San and Xiao Wu join a new academy, the "shrek academy" for monsters (yeah, no kidding). When entering, Tang San show his OPness by being only lv 29 and making a lv 76 guy go all-out.
In all, shrek academy has only 7 students. This because team matches at the colosseum (where they fight other humans) are with 7 people, and because our feeble minds can't take too many characters at once. From those 7 people, 2 are support class fighters (told you it's like an RPG), and of course they're all geniuses, because we all love OP characters in our stories.
With those students, they go into a forest to fight monsters and train. This is also where Tang San gets a rare power-up (the external spirit bone), because he wasn't OP enough already.
After that we get some more training, and some colosseum fights, but nothing special ever happens.
Art: the art works nice in sync with some other elements from the story and the characters to make the manhua as attractive as possible... to 10-year olds. Both the character designs as their personalities are so childish, it's hard to keep reading it.
Characters: as said above, they are all really childish. of course, they are really children of about 12 in most of what I've read, but they're still annoyingly childish, while at moments they're supposed to seem mature.
Apart from being childish, the characters also have no depth at all. We know who they are on the surface, and something about their basic personalities. But apart from that? They're all just paper cardboards.
Another problem I have with both characters and story as a whole is that there is no motivation for anything. These people train to become strong, but what are they aiming for? You need to use your strength for SOMETHING, right? It's quite annoying to see them train, without having a real reason.
Overall: OP characters destroy the story, the tone is really immature (strengthened by the art style), and none of the characters have any depth or motivation at all.
I would not recommend this manhua. If you really want to read the story, maybe you should try the LN.