I really don't see what major changes have been done so far that are markedly inferior to what's in the books.
Sure, Barristan Selmy was awesome and I hate to lose him, but it's not like his death ruined Dany's storyline, or altered it in any way.
Moreover, the Sansa thing (the other major change) is much more interesting than what is featured in the books.
What would Sansa do in the Vale this season?
Do we really want Stannis to ride south and get stuck in a snow storm, then trade misfortunes with the Boltons until next season?
I think having an existing Stark take over the northern rebellion stuff is much better than some character we have to learn about brand new.
There comes a point in every TV series when new characters become unwelcome. It doesn't matter how well they're written or acted. They need to be disposable, and the characters left out of the books aren't disposable, so they're not in the show.
I think the broad strokes of it are probably better than what's in the books. The issue I see is that they're not doing the best job of tying everything back into the characters.
- Barristan, at almost every turn for the last 3 seasons, has had to pass up on the chance to do anything combat related because it's more important for him to be at Dany's side to protect her. He's out for a walk in Mereen, the alarm bells start to sound, and rather than hurry back to Dany to ensure her safety, he decides to draw his sword (when no Harpies are even around) and go running into dark alleyways looking for trouble?
- After 2+ seasons of the Unsullied looking, acting, and behaving like the Unsullied from the books, they are, all of a sudden, prone to panic, will break ranks at the drop of a hat, react to pain, and turn their backs to their opponents.
- Littlefinger. Willing to wait and see how things play out, but his maneuvering so far this season is very "un-Littlefinger-like". He's leaving an awful lot to chance, as it appears now. That's not how he rolls.
- Darth Sansa. "No, I won't do it. I won't be married to a Bolton, they killed my brother." 30 seconds of Littlefinger pep talk later...."Ah, fuck it. OK."
- Varys. Spent the first two seasons actively trying to kill Dany. Lobbied against her in small council meetings. Had her spied on and reported the findings to the council. Directly sent the order to have her killed as well as Jorah's pardon for a job well done. Now, all of a sudden, he's telling us that he was actually supporting her all along?
- Jaime/Bronn. Kinda' fun, what they're doing, but completely ridiculous. The show, almost satirically, has tried to explain why they're doing what they're doing, but to say it doesn't add up for either guy is putting it lightly.
I could keep going, but my fingers are getting tired. Bottom line is that it seems like they're writing to tentpoles all over the place, and the characters are bending and snapping under the strain of it all. I'm all for cutting characters/plotlines and getting from point A to B much quicker than in ADWD and AFFC, but the biggest strength of ASOIAF is the intense character study. I feel like the showrunners are so intent upon moving the plot from point A to point B that they're starting to leave their own characters behind, and hoping that if they move quickly enough, nobody will notice.