Certain armies get a lot of flack for their new codices breaking with fluff or having absurdly many "good" units without any "bad" units. Whether units are inherently good or bad is a topic for another time, but I would like to address my favorite whipping boys for being too good, the Space Wolves. There are a lot of reasons for why this is, but I'd like to address just a few and propose why they aren't so bad as you might think and may actually be a good thing for the game.
First the lightning rod himself, the rune priest. Space wolves have historically been known as the chapter that has the second most hatred of psykers, right after black templar. They've always had their rune priests and they've always been psykers, but with the 5th edition codex they've become arguably the best psykers and that shocks some people. These rune priests strike a fine balance between offensive and support psykers, have reliable psychic stop and are priced in line with librarians. In a codex where melee characters can run into the price range of land raiders, being able to select a character who can contribute to the army relatively cheaply is a relief of pressure on building a list. He brings the ability to bring close or long range fire support, buff and debuff spells and an alternative to the focused mindset of melee stomping characters.
The issue of Wolves' hatred of psychers, specifically sorcerers, is the hang up for most people. Some people accept the GW explanation that goes along the lines of "rune priests are shamans, not sorcerers so it's cool," some don't. I think it was a necessary decision to give people a reason to bring rune priests when they simply don't stack up to the melee prowess of their comrades. But why is he good for the game? To me he is the marine psyker simplified: able to buff, debuff and contribute to the damage output of the army and having a simple version of psychic stop. Some people can argue that psychic stop doesn't need to be simplified, but for new players the rules we take for granted are daunting. Let them have some breaks so they can focus on thinking about the game rather than the rules.
Next another point of "ridiculousness," the grey hunters. These are the space wolf troops you've probably seen if you've played against wolves. They come with the standard tactical layout plus a ccw, trade combat tactics for counter attack and have no sergeant, so they are leadership 8 for one point less than a tactical marine. For that one point reduction, you get an extra attack in close combat and the possibility (72%) to double tap your boltguns (and possibly plasma) and then get the same number of close combat attacks that you would if you had fired your bolt pistols and assaulted. This allows space wolf players to have more flexibility in their tactical choices without leaving them in a very bad situation.
The idea that these are your "tactical" marines is one of the causes of discontent over the codex. These are not tactical marines. Tactical marines focus on nothing and diversify, able to bring a heavy weapon, special weapon and a sergeant with a special combat weapon. Grey hunters do not have access to heavy weapons and their ability to take a second weapon (for free) is offset by their inability to utilize a transport if they want a sergeant equivalent. While they can take close combat special abilities (PW, PF or Mark of the Wulfen), each of these is on a model with one attack base and the lack of a sergeant keeps the squad at leadership eight. While this is low for marines, it is pretty average for the game.
These are only some of the points of contention over this codex, but thinking about the codex in the whole of 40k. This codex is versatile and forgiving, almost to a fault. It simplifies 40k and makes it easier to learn and win with while learning. This is good for beginners. Go back and read that last sentence before you start flaming. The codex is good for beginners, not only good for beginners [Tasteless comment retracted], but it gives beginners a more gradual learning curve, allowing for them to win while they are learning to play. Winning is what we call in teaching "a positive reinforcer," meaning it makes people want to repeat an action that led to the reinforcement. New players wanting to play more 40k helps bring them into the game more. That is good for the rest of us by giving us more people to play against.