Okay, personal choices, or whatever. I kinda have an unfounded soft spot for Victarion Greyjoy, personally.
I'm talking about the guy showed thus far, who is completely and thoroughly about self-indulgence, in a way that the book character was not. It was not, for example, an allusion to his sexuality, either in its focus or lack thereof. While Oberyn in the books might have made some impulsive or precipitous choices, they were strategic or tactical decisions, regarding which course of action to pursue. He made some of those from his heart, in unwise fashion, but not out of an inability to restrain his impulses. His choice to personally involve himself in Tyrion's trial, for instance, was premeditated, and no doubt with full consideration of the ramifications of the diplomatic difficulties he would engender with that involvement. He did not suddenly stab a Lannister loyalist or lesser House member, because he heard him singing their theme song. His own anecdotes to Tyrion bespeak a contempt for the sort of individual who cannot restrain his appetites or passions (i.e. the Tyrell governor who was supposed to be administering a conquered province, not indulging himself). Even his technique against the Mountain required discipline and patience to carry out with a hope of success.

Next to those qualities, the guy we have seen on the show, lashing out at flunkies just because he can, and placing personal enjoyment before diplomatic duties IS a degenerate.

Entirely possible from what I understand. There was supposed to be a gap, particularly in the storylines of the younger protagonists to allow them to grow into their ordained roles, of greenseer (Bran), noble heir (Rickon), mistress of intrigue (Sansa), assassin (Arya) and conquering queen (Daenerys), and for the dragons to get all rideable. That last was alluded to in an interview or something, by Martin himself. Then, as I have heard, he started realizing that the flashbacks to explain how certain characters got to the point where they were meant to get, required too much explanation, so eventually he abandoned the time jump, and aFfC was born. Thus, it is very probable that Daenerys was one of the characters who required filler while others were having their development, according to the original plan.
Yeah, but all kinds of stuff gets teased, like Sean Bean as the hero of the thing. Any viewer who expects the rug to remain under him at this point is an idiot.

They might have started that process. IDK if this is just me, because I've found her to be pretty much insufferable since early in season 2, but it does seem like they are taking the "high & mighty" thing to a point where it is starting to look like arrogance. It certainly seemed like they were trying to make her adulation by the liberated slaves in the finale last year to be a mix of exultation in her triumph and unease at how bad it can still get.

Importance can be highly subjective, especially for a work still in progress. The little details hide easter eggs and mysteries that clarify stories of which we think we know the whole truth. R+L=J being one such issue that only emerged from attention to those little details and the picture they painted in the aggregate, rather than any direct reference to that possibility. The mystery of the Knight of the Laughing Tree goes a long way to explaining the motivation of the Reed kids for helping Bran at such great lengths, because it explains the genesis of the loyalty between Howland Reed and Ned Stark, and is yet another example of how the passing between generations of loyalties, favors, feuds and insults determine how sides are chosen, and thus the outcomes of current conflicts. A point explicitly referenced in those conversations between Oberyn and Tyrion, which the show has seen fit to elide in favor of having him select prostitutes.

As for the descriptions and details, people love to bitch about those, but they convey the flavor and experience of the different characters. It seemed like pointless verbosity for Robert Jordan, until Brandon Sanderson came along and showed how hollow and discordant the story and characterization becomes when they are missing. You might roll your eyes at the details of the meals, but without those details, you don't grasp as clearly when the characters are close to starvation or in the lap of luxury. The privation of the march to Winterfell is felt so keenly, because we're used to four previous books' descriptions of what constitutes food for nobles. The "roughing it" of the Lannisters' campaign in GoT is a long way from the sort of fare armies are settling for in DWD. Those details contribute to the sense of alieness and being out of place in Daenerys arc.

Event little things in the conversations, where "all they do is talk and nothing happens" reveals the circumstances and condition of the characters. For instance, one apparently pointless conversation between Daenerys and Barristan concerning his departure from King's Landing and journey to her service, has her break it off and run to her dragons. Sure "nothing happens," but we know the significance of the characters' totemic beasts, from the ramifications of Lady's murder, Grey Wind's marginalization, and Nymeria's reversion to savagery, and the confinement and estrangement of Daenerys' dragons is a critical symbol of how she is ill-suited to be ruling Meereen. And that conversation she breaks off to visit the dragons? Barristan's tale begins with the statement that he was hunted for telling a child monarch the truth, but "the truth was not welcome in that court", only to have Daenerys essentially refuse to hear his assessment and attempts to tell her the truth of Ned's morals and lack of enmity towards her(remarkable, considering what her father did to his, and what I said above, re: generational enmity).

The books build an atmosphere around the reader, so he takes in the bastardness of the characters, like the air beneath his wings, or the water against his gills, while the show has to lurch between explicit demonstrations of the same, leading to the general dissatisfaction with Jaime's actions this week.

That medium is stupid. It's not called the boob tube to explain the obsession Weiss & Benioff seem to have with female anatomy. This show is to an excellent fantasy series as a History Channel documentary is to a history book.