I can't help but agree with most of what you said here. Up until this particular storyline, this book has been pretty good with some solid writing.
This storyline had the potential to be a great one, the elements were there. But I wasn't given a reason to care about Sarko because the writer didn't provide any. What made Sarko turn out the way he did? He was the Alley Rat's son for crying out loud. Why did Sarko think that reviving the Sinestro Corps was the only way to go? That and more the writer fails to answer. There was no proper set-up and the reader was not given a reason to care. Sarko was nothing more than a one-note villain. His death and the pain that it brought the Alley Rat fell flat on it's face. All of this would have had far more impact had proper storytelling techniques been used.
Then there's Krona's Gauntlet. It gained sentience and yet this isn't explored in the least little bit. We're given a half baked explanation as to why and how it gained sentience and then it's left at that. The Gauntlet changed Hal into a being of willpower. How did it do that? The gauntlet gained sentience? How did it gain it? It's not entirely clear since the writer focused so little on an explanation. Worse, instead of reasoning with it, or trying to, Hal simply kills it.
Twenty-one issues in and we still haven't seen any exploration into Hal being made of pure willpower. Does he have any additional abilities aside from being able to create a ring from willpower and sensing fear? Does Hal still need to recharge his ring or does his body of willpower keep it charged? What else can his ring do? Is it more powerful than a standard power ring? Being made of pure willpower, does Hal even need the ring? There are so many questions about this and yet, they are all going unanswered. Which begs the question, why even turn Hal into a being of pure willpower if nothing is going to be done to explore this?
Looking at future solicitations, I hope things will get better for this book. Venditti can do better than this and I hope to see better from him.
Perhaps Hal is evolving into a new form of Guardian?
Or perhaps thanks to the gauntlet Hal is now hosting a new version of ION?
If Hal is truly made of willpower, I would think his powers and abilities would be about the same as
1. Alan Scott in his SENTINEL form
2. Kyle when he was ION
However Hal's thinking tends to be a bit....linear, to say the least.
When he was stuck with the blue ring on his finger, he kept trying to sincerely hope for something grand like world peace to activate the blue ring, only to turn out that his sincere hope was the blue ring would stop nagging him.
When he put on all the yellow rings and charged them in the Sinestro Corp War due to his green ring being drained, he was using the power and felt that he understood the power of fear until Sinestro easily schooled him.
So his tendency to be straightforward and linear in his thinking and his desire to be a GL may be blocking him from using his full power as a being of will.