I just think the N1K is over-rated because it's not very fast and its 20mm ballistics are average. Secondly, the airplane only excels at furballing, and is more or less helpless vs. hit and run tactics in a multi-aircraft engagement. The most effective N1K pilots are great shots who kill with the smallest window of opportunity; I know when I've run into them because I end up in the tower. 
Perhaps I should have added that it's in comparison to its popularity versus the weaknesses I outline above that I think the N1K is over-rated by a lot people. Is that more clear? It might not also merit an ENY of 5 save for the fact that so many people
put themselves into a position where it's easy for a N1K to get a killing shot. I do it now and then myself, but know where to place the blame.
Besides the ground attack comments, which I don't think are a very big deal, I'll respond to your charges.
1) No one has ever accused the N1K of being fast. Therefore, its speed can not be over-rated.
Sure, I suppose not. That sounds logical, but pilot behavior in the arenas often contradicts sober rationality. Don't we love it when we see N1K pilots push their aircraft into situations where only a faster aircraft will do?
2) 20mm balistics are well-known to be average at best. So, who ever called them lazar accurate? Again, not over-rated.
The cannons are probably 50% of the reason most N1K pilots fly it, so you make my argument for me.
3a) Only good in a furball . . . Well, to some that is the only way the game should be played, so how does that make the plane "over-rated"?
If you think furballing is the
raison d'etre of aircraft combat simulations then you are over-rating all aircraft that excel at it when they underperform in other areas. Personally, I think furballing has its place and can be a lot of fun, but I take a more rounded view of all the different ways that are fun to kill the enemy, e.g. ground attack, bomber intercept (N1K would be great if it weren't for speed), energy fighting, level bombing, bomber escort, etc. Moreover, the N1K may be great at furballing, but I wouldn't be too excited if I were assigned one in FSO, for example.
3b) The N1K carries enough ord to be a bona-fide threat against any GV, ergo your "furball only" comment is erroneous once.
3c) The N1K's guns are capable of easily killing any soft-skined GV, ergo your "furball only" comment is erroneous twice.
3d) The N1K's guns carry a lot of ammo and can easily take down buildings/troops/ords/dar/field guns/etc., ergo your "furball only" comment is erroneous thrice.
3e) The N1K's guns carry a lot of fuel and ammo which makes it an excellent choice as a base-cap / vulcher, ergo your "furball only" comment is erroneous four times.
3f) There are other things the N1K can do that are not "furball related" but I think the point has been sufficiently made.
Agreed. It's a pity that it's not put to more use in these areas.
4a) Helpless against hit and run tactics?
Perhaps only slightly less than the HurriIIC.
4b) "Helpless vs. hit and run tactics in a multi-plane engagement"? Just what exactly is your definition of a plane that is NOT helpless in this situation? I would suspect you mean planes with enough speed to run away from . . . er . . . "extend and reset" the fight? If not, please enlighten me.
Yes, basically I mean it helps to have a faster airplane to defend against attackers that will only fight on their terms. That is, a flight of N1K's are in big trouble if they are engaged by F4U's or P-51s (insert faster plane here) that use energy fighting tactics. Save a lucky snap shot, their opposition won't let the N1K's get close enough for the cannons to matter. The Ki-84 is another story, and to me is superior to the N1K because it is faster, climbs better, and accelerates better; these are the more important attributes in multi-aircraft acm.
5) Need to be a great shot in a N1K for it to be effective?
With 900 cannon rounds, it suits my "spray-and-pray" style just fine, thanks. 
When I die to a N1K pilot it is usually because I let them have a tiny snap shot and they nail it. Short of that I don't give many opportunities for effective spray and pray shooting. It frequently happens that a N1K pilot sprays at 800 yards out while I extend away. Sometimes they take off an aileron or knock of a flap and I have to rtb, more frequently they miss or do superficial damage. Unless your target has poor SA, you need to be good at snapshots in the N1K because that's all good-SA pilots will give you, and some would say they won't even give you that.
So, again, over-rated it isn't. It does many things well, especially in the MA environment. Even I can get kills in it, which must mean it is a capable aircraft. IMO it earns it's ENY 5 rating honestly.
I think you're entitled to your opinion... but I see so many pilots in N1K's who don't know what the heck they're doing it causes me to suspect that they believe the aircraft will make up for their pilot-skill shortcomings, when in fact we all know the silver bullet they're looking for is the Spit16.
