So I guess now I'll respond to Mike's question and post a quick "what I thought of the manga and the canon material that leads up to Final Act"
Overall I thought it was typical InuYasha, the manga moves at a really quick pace and is probably one of the best weekly manga I've read in terms of being a weekly series. Every 3-5 chapters whatever little mini story line is finished and you move onto the next little mini story line and these mini story lines form a line that tell the main story. I was also pretty surprised at how bloody the manga was compared to the anime, there is quiet a bit more blood and we see a lot of villagers getting mauled by demons. This really stood out in the birds arc when we had demon birds pecking people and blood blasting out. This isn't really a gory series (it's no Hellsing) I'm more surprised it's there at all.
Doing a quick run down of the arcs
-Search for the next world
This was probably the longest arc and introduced us to another incarnation of Naraku, Hakudoshi who I enjoyed quiet a bit. He makes a great right hand character for Naraku and gives off a very smug attitude which works well coming from a younger character. His horse was cool for all of 5 minutes before it go killed... Overall he's been a good addition to the series and I look forward to seeing him more.
This arc also introduced the minor villain Princess Abi who I never really cared for, outside of the above mentioned violence from birds she really felt like a plot convenience character who was simply introduced to give the cast a method of getting into the next world after the failure of getting though the gate. The really major part of this is that it brought back Kikyo... again, and worse Kagome is the reason Kikyo survives, and then she gets mad/jealous when InuYasha starts thinking a lot about her again. What was the point of "killing" Kikyo is you were just going to bring her back again? When people accuse InuYasha of spending too much time going in circles it's moments like this that really stand out.
The other major plot development in this arc is the return of Kohaku's memories which I really enjoyed. Having him now aware of the terrible things he's doing/has done while still doing them in order to stay close to Naraku to try and help defeat Naraku is a very nice direction for his character and all the Kohaku and Sango scenes have a lot more impact because of it.
This arc did have a great pay off when InuYasha and co follow Naraku into the next world, the whole battle down there is great and I love InuYasha's new attack and sword upgrade. The story behind why he gets them is great and it gives InuYasha a different looking attack that feels unique to help diversify him move set. I have no idea what the dub attack for this name is because the translation I read often left the attack names in Japanese and even when it did translate them it was a literal translating like Cutting Wind instead of Wind Scar. Also Sesshomaru gets a bad ass scene where he beats the statues that neither InuYasha nor Naraku could beat and saves the group.
Rats mini arc
I liked the idea behind this more then the execution. The stuff with Sango and Kohaku was great, but I never felt like that rats were any kind of threat. Yeah they devoured human settlements but they never really tried to attack any of the main cast and were easily enough taken out. This arc would probably be more enjoyable animated because in the manga it was mostly lots of pages full of white circles in a pack.
Canon filler arc
I had to keep reminding myself that I was reading the manga so these scenes were in fact canon despite feeling like anime original content... in the manga. We get a story line about Shippo being possessed by a bug demon, and another fucking story about Miroku having promised himself to a girl years ago and Sango getting jealous again. The Shippo story line was horrible, the Miroku one at least had the decency of having the one good scene where Miroku gets angry about the demon trying to take him women (Sango). These two story lines really helps to see why InuYasha's filler content is good, it's hilariously easy to write an InuYasha story line and make it feel like it belongs in the series.
Goryoumaru arc
I hate this character, his design is stupid, how he acts annoys me, and based upon how this arc ended and the Toonami preview for Final Act he's apparently still around and going to be more important. This arc start promising with kids with big laser guns killing demons and I was really hoping we might get InuYasha and co killing little kids, sadly my sick fantasy was not to be. I really don't have much to say about this, I read it late last night and actually started falling asleep while reading it because of how mediocre it was. Considering this is apparently one of the last canon things adapted in the original anime that's a shame.
I forget when it became relevant but I did neglect to mention the new plot item, an orb that the baby holds because the baby is Naraku and Hakudoshi's heart and this orb makes him basically invisible to InuYasha, Kikyo, and Kagura as it makes people unable to sense demon energy. It's a good idea and I look forward to seeing what else they do with it in Final Act because it's still an unresolved plot thread.
Also I did like the chapter where Kagome went back to her own time and her friends FINALLY met InuYasha and pretty much liked him. InuYasha in the human world really is the best part of the series filler or canon.
So that's my thoughts on the canon content between the 5ish episodes after InuYasha stopped airing on Toonami and where Final Act picks up. Very much looking forward to Final Act tonight and I will work on finishing the rest of the original InuYasha anime over the next few months.