It's a risky tactic to be sure. At its most basic level, it makes Cleave and Great Cleave more useful. I'm not positive that they improved it for the express purpose of using it to fix iterative attacks. From my understanding, it's more the answer to the wizard spells that affect a number of targets at once, like fireball.
Seems to me they should've renamed it Lesser Whirlwind Attack, because that's basically what it is. I never did see how high Strength let you hit another opponent after the first was down
Their answer to iterative attacks being useless is Vital Strike and Improved Vital Strike, which allow you to multiply weapon damage if you only swing once. The only other fix that I can come up with to fix iterative attacks is to decrease the attack bonus difference between your first attack and subsequent ones. If you make it a -2 or -3 instead of a -5, those attacks are no longer useless in most cases.
I was thinking about reducing the number of iteratives to 1/10 BAB. At +10, you get a second attack at +5; at +15, you get a third at +10, and that's it - no more. The third/fourth attacks rarely, if ever, hit against a level-appropriate foe unless you're a fighter. This would be a simple solution - easy to convert, and fewer attacks to roll. I haven't actually tried it in play, though, so I don't know how it would work out.
D&D doesn't use the "spiral of death" mechanic thus as another poster alluded to it is always better to focus your full attack on a single opponent til their downed, THEN attack another creature.
Allister's right. Whirlwind Attack is nigh useless except against hordes of low-level creatures (which you'd rarely be fighting by the time you could qualify for that feat). It's basically the same thing as the rule in 1E that fighters could make 1 attack/level against creatures under 1 HD.
It's a risky tactic to be sure. At its most basic level, it makes Cleave and Great Cleave more useful.
The new feats are useful, sure - you could hurt 2 opponents, giving the flanking rogue a better chance of downing one (especially if he's using that feat from PHB II, Opportunistic Attack or whatever it's called). I think it was developed to get away from the "full attack on one opponent till its down" syndrome - IOW, contribute more to cinematic combat. In that regard, they succeeded - instead of strictly concentrating on ONE opponent, you can hit two (or three, or more) during a single round. I think they need higher prereqs, though - maybe a minimum BAB - because being able to hit umpteen opponents in reach at your highest BAB is a huge advantage.
Compatibility: Of all the goals I set out with when designing this game, compatibility ranked near the top. I wanted to make sure that any rules we changed were adaptable to the extensive body of work that exists for the 3.5 rules set. In addition to being compatible, I wanted to ensure that any conversion work would be minimal.
I am so freaking tired of everyone crowing about "backwards compatibility". Read the above statement. Does the word "backwards" appear anywhere in there? No. 3E and 2E were compatible - you could convert your 2E material to 3E with a little work. Same with 3E/3.5. 4E is not compatible with 3E (this is not a bash on 4E, just a simple statement of fact). Jason's stated goal is to make PF compatible with 3E, so that you can convert stuff with a minimum of effort.
Conversion will be necessary. Live with it. If you don't want to convert stuff, stick to 3.5.
I think its valid to dispute the claim that PF unnecessarily changes viable features of the game by pointing out that we're currently enjoying a new version of D&D, (from the owners of the brand), that does the very same thing.
Who's this "we", kemosabe? *I'm* certainly not enjoying that new version of D&D, and I suspect a lot of the folks here who are playing Pathfinder aren't either.