Way back when, I used to play Champions quite a bit. Started with 2nd edition, then moved to 4th with the Big Blue Book. Played in a Fantasy HERO game for quite some time, really liked it. I used to be a major GURPS fan, but thought HERO was more succinct and simpler. Then 5th arrived, which was mainly just a clean-up. When 6th came out, I pre-ordered, instantly did not like it. No particular reasons why, my immediate reaction was apathy and no desire to play. In retrospect, I was misguided for a variety of reasons. Yes, 6th edition is not a game. Much like FUDGE, it requires work to create a game. And honestly, any sort of rpg you want to create is possible within the framework of HERO. But again, it requires work. You can't just pull it off the shelf and start playing, it takes a lot of work to get started. Some people dislike that, and many times it's easier to just play D&D because there's literally no work involved at all. Still, sometimes you want a custom environment with specific paradigms and this is where HERO excels.
There are some changes in 6th that bothered be at first, but now I see the reason behind the madness. No more figured characteristics. Defense is no longer tied directly to DEX, which at first seems illogical, but in reality is perfectly acceptable. Not every Olympic gymnast would beat ass in the MMA, and in fact they'd probably get killed. And I'm sure most MMA fighters would be hard pressed to do anything resembling Gold Medal gymnastics. So there's that...again, I thought it was annoying at first, but now I like it. A lot. Customizing a character is much easier because of this. You can have a frail old martial arts master who can barely scoot along that is impossible to hit. And you can have a guy with ridiculous ability shooting arrows that can't palm a coin to save his life. A few other changes to powers, well, I didn't know the system well enough anyway to have a preference, but it looks like it works well enough.
All the upfront costs with HERO (character creation can take hours) are weighed by the simplicity of the system itself. Once you have everything ready to go, play is nothing more than rolling 3D6. The combat system is straightforward, the effects that powers have is extremely simple, and there's hardly any need to look at charts/tables/whatever. There have been knocks on rolling large numbers of dice, but unless you're a total moron I can't see it taking more than 5 seconds, even with 20D6 for instance. The phases of combat using the SPD chart are extremely nice; there's very little argument about who gets to act when, and in what order. Tactical combat is thus very satisfying. For some genres, this is a huge bonus, for others it's a pain in the ass. Thankfully, there is little need to use all the rules. In fact, you can get by with very few of the rules if you decide complex combat isn't for you. I have the Advanced Player's Guide, and after looking through that I can safely say I'd probably use absolutely none of it UNLESS I wanted to run some sort of tactical board game, in which case it'd be awesome. The flexibility of the system is rather surprising, much like Basic Roleplaying is still relevant.
Some genres I think HERO 6th would work extremely well include supers (obviously), but only if you expect a lot of flexibility. Multipowers and Variable Power Pools make characters like gadgeteers and mages easier to create than in other systems, but that means even more work. Again, that appeals to some people, but not others. I still like DC Heroes and Marvel in most circumstances, but for grittier games HERO would be ideal. HERO can do fantasy pretty well, but again it depends on what you want. For D&D-type games, I think it'd be a pain in the ass. But for a magic system like I discussed in my previous post, it's the way to go. Trying to work out a magic system is what prompted me to revisit HERO in the first place, so yeah...the 6th edition of Fantasy HERO is a very nice book, by the way, even if it's quite expensive. SciFi, pretty good. I have the 5th edition of Star HERO and have ordered the 6th; again, a nicely written book. Cyberpunk I think would work. As much as I enjoy playing Shadowrun, the system is rather shitty. It's easy to port the background to HERO, almost too easy. Westerns, hmmm...at first I'd say no, but honestly, the combat system would help tremendously for things like dramatic shootouts. Horror would be problematic, unless it's something like Delta Green. Call of Cthulhu would not be viable, but I've read that they're working on a Cthulhu HERO book coming out at GenCon. I'd like to see that. Overall, the system is simple enough to accommodate just about any sort of genre that is skills-based. Games featuring iconic sorts of characters (D&D once again comes to mind) would be watered down and less fun, so it's definitely not a system for all purposes. But again, I'm surprised that I truly think the game system is great, considering I dismissed it for the past two years as oppressive and clunky. At its very core, HERO is a solid, simple system that can be used for a variety of purposes, to build some fun games.
As a final note, the main books are massive...and yet, the rules can be distilled down to two pages. The Basic book is all you really need to play anyway. But to reiterate, there is a lot of work and effort that needs to be expended in order to get to that point, which makes it look like a serious pain in the ass. If you can handle the initial costs, I think the system itself is fairly solid.