These three ways are...
1) Basic Entertainment Value
2) Artistic Merits
3) Commercial Merits
These three frequently correlate well with one another, but sometimes, they may be inversely related - for example, a show may have few artistic merits and be of questionable entertainment value, but still sell like Tim Horton's coffee in the dead of Winter. On the other hand, a show may have substantial artistic merits and be of great entertainment value, but sell like sand castles in the desert. It almost goes with out saying that evaluating the basic entertainment value of a show is a subjective game, much like charades, and less of a clear-cut game like Monopoly. So, when I speak of entertainment value I focus purely on what I, personally, took from it. For artistic merits, and commercial merits, however, I'll try to broaden my horizons a bit.
So, first, let's take a look at Basic Entertainment Value.
Endless Eight is, in either one of its eight iterations, a fairly nice and eventful slice of life anime episode. There's no buxom babes shooting eye beams at wonderful witches or giant NGE angel rejects destroying schools or gorgeous teenage assassins trying to knife Kyon, but it does have a lot of charm and style. It also has plenty of pleasing fan-service, I must admit. Including this ultimate highlight of low(er body)lights... ;)
Typical fan reaction to this shot?:
Well, what more needs to be said? :D After the first three or four episodes of Endless Eight, though, Haruhi, Mikuru, and Nagato's bikini wardrobe, and Kimono choices, was about all you had left to look forward to - the rest was painfully repetitious. It became like eating ten pounds of dry, tasteless vegetables for a few ounces of the sweetest ice cream ever. But then, admittedly, the conclusion to the arc is like a sizzling filet mignon with a side order of potatoes lathered in scrumptious cheese. A lot of crap, but with a nice dainty payoff... dainty in more ways than one, *ahem*. ;)
Overall, I'd probably give Endless Eight a 5 or 6/10 for sheer entertainment value. It could have been worse - it could have been Nagato reading a book for 20 minutes in each and every episode... but it could have been a lot better too. Heh.
Moving on... Endless Eight was a bold artistic gamble, no doubt. While it reflects the anal retentiveness of KyoAni ( "It has an eight in the name! We simply must do something with that!" ), it was nonetheless a ballsy move, with potential artistic merits. However, KyoAni's creative vision in arc concepts was undermined by their refusal to break from the source material to any significant degree at all. Truthfully, I think that JC Staff, an anime company known for loving to produce anime original material, would have done much more with this arc concept than KyoAni did. KyoAni is a company with bold artistic vision, but with out the details men to execute it in an equally eye-catching and flamboyantly artistic way.
Overall, I'd have to give artistic merits about a 7/10.
So, that leaves us with Commercial Merits - probably the most important of the three categories. It is also the one I've given the most thought to. What lasting impact has Endless Eight had on the Haruhi franchise, and on the Haruhi fan community? Well, the Japanese fan community is probably already back into the swing of things - from the few Japanese fans of Haruhi that I've read comments by, I get the distinct impression that their patience for stunts like Endless Eight is probably greater than that of your western viewer. They also seem to pick up on nuances and subtleties better than a lot of us western viewers, I think. Perhaps it goes back to what I heard about how romantic courtship tends to work in Japan - it's all based on intuiting what your desired partner wants, and then acting upon that. This takes a keen eye to detail, and a patience to absorb every pertinent idiocentricity or intricacy. The Haruhi DVDs will probably sell Ok, or close to Ok, in Japan, even with the EE effect. The K-On art style also sells quite well over there, so I doubt that the Haruhi art alterations will hurt Japan sales. So, as it pertains to the Japanese fan community, EE's effect is probably negligible. These are hardcore fans that won't shake easily. But what of the foreign market for Haruhi?
This is what I think here, based on trying to take a careful reading of Anime Suki fan reactions, various anime blogs, and what pop culture sites have had to say on the matter... EE has created controversy, and perhaps some lasting fan rage, no doubt about it. Personally, I view that as worse than positive hype, and worse than 50/50 controversy... but it is better than pure apathy. Again, it would be worse if there was no stunt, but the episodes were boring anyway. OTOH, more Disappearance would have been better than this. That, I think, is the inescapable fact of EE for most of the Haruhi fan community. So, the lasting widespread impact of EE will depend on one thing - how soon we get Disappearance.
What EE has ironically done, in my estimation, is set the clock timing down. There's no more redoes for KyoAni - there's no more endless opportunities within endless loops of foreign fans grovelling for whatever scraps they can get from one year to the next. I personally get a palpable sense from broad swaths of the western Haruhi fan community that Disappearance needs to be done, and needs to be done soon. It's simmering just below the surface, as a Haruhiist's hope and faith is not easily shattered, but KyoAni and Kadokawa's images have become murky, and it's up to them to deliver.
If Disappearance arrives, with good art style and animation, before the end of 2010... then EE will become simply a bad memory, or even a somewhat comedically fond one. But what EE has done is drain away another quart or so of the blood of patience from the body of Haruhiists. So now there's less patience there. The Haruhi fan community has suffered some permanent losses due to Endless Eight - but EE's controversy may give it some gains to make up the difference, I'll admit. Still, very soon, KyoAni and Kadokawa will have to deliver. I think that they have until the end of 2010. If there's no Disappearance (and Disappearance done well) by that point, then I think the fan community will start to bleed off badly. At that point, I'm even a bit uncertain of the domestic Japanese fan community. That's my current outlook on the Haruhi anime. KyoAni and Kadokawa haven't killed the franchise... but their actions have eroded their image in the eyes of the fans, and have started the clock ticking down on them. Any comments and feedback are most welcomed! :)