I thought it might be worthwhile to explain some of the things that makes the HERO system unique for those that have never played it.
So to start the thread off and provide an example I thought I'd talk about my favorite part of the HERO system: the concept of special effects. The separation of what the power DOES in game terms, from the way it looks is a vital part of what makes the HERO system work. Lets say you want to build a character that is based on fire, and another that is magic based. And lets say they both have a power that does 10 d6 of normal damage at range.
The Fire Character buys it as "Fire Bolt": An incandescent spear of pure heat that flies from his outstretched palm to blast his target.
The Magic Character buys it as "Invocation of Askarial": An evocation that creates a shimmering winged form of astral energy that fly towards the target and smites it with a glowing energy sword.
BOTH powers can be bought as exactly the same power in game terms, 12 d6 Energy blast. 5 pts per d6 = 60 pts base cost.
Now if they want it to do something more, like they want it to reduce some types of defense or it only works at night, then those would be advantages (for ignoring some defense) or limitations (only works at night) that would modify the base cost. Advantages and Limitations are multipliers that either increase or decrease the base cost of a power.
Many folks look at the incredible flexibility of the HERO system and say that it's all too complex, but really it's not. You see, the job of the GM is to choose WHAT parts of the system he wishes to use. Many campaigns choose to simplify aspects of the game by ignoring sections of the rule set, like Knockback, or body damage. Simplifying movement rules and initiative. Determining the flavor of the campaign by imposing certain limitations universally (all magic use must have a verbal component, so everyone knows to gag a mage) or all mutants are susceptible to a particular toxin that is totally ineffective vs tech based characters.
What HERO system really is, is a fantastically elegant construction kit to allow you to build ANY kind of world, powers system, characters and game that you want. If you look at all the rules and assume that you have to use ALL of them in every game, well, yeah, it's pretty complex.
Just keep in mind that you're looking at a superset of ALL genres and game types. Use only what you need, simplify what you want to and make it unique and fun for YOUR group
What it comes down to is this:
When my kids come to me and say: "Dad, we want to play a game based on on the Fablehaven books, but we want the fairies and the magic preserves to be in space and set on orbital colonies" Well, I know EXACTLY what set of books to reach for
How about you? What aspect of HERO system do you think folks should know about?