There are 3 reviews of the Marvel Heroic Roleplaying system on RPG.net. They give it 5, 4 and 3 stars respectively for system design. (All three give it 5 stars for style.)
Here are some extracts from the
3 star review:
Most of the powers are left purposefully vague, leaving the Storyteller and the players to add in the blanks, usually based on their knowledge of the hero or villain they’re playing. This is a problem, since it is obvious that Mister Fantastic’s D10 Stretching, for example, works in a very different way than Carnage’s Stretching. Let’s take Elemental Control, which is a general moniker for Air Control, Cosmic Control, Darkforce Control, Earth Control, Electric Control, Fire/Heat Control, Gravity Control, Ice/Cold Control or any other type of energy one can come up with. No rules distinction is made between any of these types of control, leaving Storytellers with a general description only. The system is remarkably flexible, allowing for ‘Complications’ that can mirror just about any effect, but you really need to know the characters in order to be sure what they can do with each power. When you’re used to playing the Hero System, Fuzion or even Mutants & Masterminds, where powers are so well-defined that they’re virtually impossible to misinterpret, this is a major worry.
Another problem with powers is their very limited effect range. All Powers use either a D6, a D8, a D10 or a D12, allowing for only 4 levels of Power. In the Basic Game, Armor, Beast, Iron Man, Luke Cage, Ms. Marvel, Sentry, Spider-Man and Spider-Woman all have the Power Superhuman Strength (D10). This may be cutting it too close for a lot of gamers and comic fans, as many of us love to compare statistics and discuss who is the stronger hero, etc. . .
[T]he number of dice in a pool and the limited range of the powers and Specialties also means there aren’t enough differences between the characters. This evens the playing field a little bit too much, allowing for minor characters to beat major league players too easily, for example.
I don't know about anyone else, but I see strong resonance here of complaints that 4e PCs are too "samey"; the related complaint that relying on narrative context and framing to carry story load (eg the difference between different heroes' powers), rather than imbedding it deep into the minutiae of the resolution mechanics, "is a major worry" reminds me of concerns that 4e loses the difference between fighter and wizard because both have a +10 to Aths or Endurance at 20th level; and the concerns about lack of distinctions among elemental/energy control powers reminds me of the oft-expressed concern that a 4e fireball can't set flammable objects on fire.
In my view, the response in defence of both games is very similar: for instance, in 4e the differences in stat, training and items for a 20th level fighter compared to a 20th level wizard mean that one will frequently succeed at challenges using Athletics, whereas when the other is called upon to make an Aths check the whole table will grown; and in Marvel Heroic the differences between two heroes (eg Spider Man and Luke Cage) will emerge not thru a single rating for their Strength, but through the totatily of their descriptor sets, and the very different ways these are able to be drawn upon and combined to frame quite different responses to challenges.
Again, in 4e, the response on the "fireballs aren't fiery" front is to point out that this is to be adjudicated by the GM, drawing on the damaging objects rules - the game treats damage to creatuers as a mechanically settled matter, and relies more on fiat, negotiation and context to handle damage to objects and scenery. And the response in Marvel Heroic on the energy/elemental front is similar: when it comes to a villain trying to blow up Spidey, there is no mechanical difference between a wind blast and a fire blast - both are resolved the same. The games mechanics for this are clear and settled. But when you want to use your blast to (say) destroy a building - or when you are targetting the Human Torch rather than Spidey - then the players, and especially the GM, are expected to adjudciate the difference between wind blasts and fire blasts as part of what is involved in framing and resolving the conflict. So the difference between wind and fire will not express itself in the minutiae of resolution, but rather in terms of what sorts of conflicts can and can't be framed, and what sorts of outcomes the GM narrates. Much as in 4e. (Though 4e has a more robust keyword system than Marvel Heroic, which - given the ranage of abilities is obliged to handle - plays a bit more fast-and-loose.)
I've got not doubt that the 3-star reviewer of Marvel Heroic knows his preferences, and wouldn't particularly care for the game. But in understanding how others are playing and enjoying it, the question to ask is not "Why don't they mind playing same-y heroes?" but rather "What techiques are they using to achieve story differentiation, given that the mechanics in their most basic form appear not to do that?"
Similarly with 4e, the question to ask is no "Why don't they mind fighters with mind control?" but rather "What techniques are they using, and what is their undertanding of the fiction such that, in their game, an effect like CaGI can take place without anyone in the fiction using mind control?"