- Was nice to see the Starks persevering as they were one of the hardest hit through the series and in the end they end up ruling the 7 kingdoms, having their own independent state of the north, potentially expanding their reach with Ayra heading off on sea etc..
- Given the timescale that was given by HBO to finish it off, on reflection there were some pretty good scenes in the final series and some spectacular set pieces, remember this is a TV show in the end, they just delivered about 4 films worth of content in terms of runtime. Just let down a bit by how much needed to be crammed in to try and get some sort of ending. With a series as popular as GOT very difficult to get a fully satisfactory part, so many far reaching stories to try and tie up. Remember that for most of the series leading up people were complaining that there wasn't enough action, we weren't seeing the Dragons in full flow often enough, story not moving quick enough.
On the first point, Bran is in charge of a completely broken city, the north just broke away with no consequences, as they aren't now contributing to or profiting from Kings Landing or the 6 kingdoms, they have no reason to keep their army there. Basically Bran has no army, no power, no money, the city is trashed there are almost no people there but he has a council of mostly failed idiots who he basically left alone immediately to 'run' his kingdom while he apparently went off to track down Drogan who is likely on a different continent (which may or may not matter).
Every other kingdom will break away, basically the ending was a joke because the actual situation that was left wasn't sustainable or worthwhile, which makes that ending pointless.
On the second part, HBO said D&D could have literally as long as they wanted. They wanted a full series run, they just got almost 20mil actual viewers for the final episode, it had huge numbers, it was profitable and they were happy to go years longer.
D&D insisted, against HBO's wishes, against GRRMs wishes that instead of going to at least 10 full series, they wanted to finish it off with two more series and 13 episodes. Basically they had offers on the table, huge offers because frankly up to season 6/7, it was great. One of those was doing KOTOR for disney with stupid stupid money on the table.
They trashed the series, finished it early and condensed the story because they had other even more profitable work to go after. HBO said they wanted 10+ series and GRRM said he always saw this being 12-14 seasons.
Honestly the series was at times too slow, some of the conversations and plot points pretty much weren't going anywhere and it could do with speeding up.. a little, not cram 5-6 seasons of content into 2 shortened seasons which also throws so much of the previous ideas to serve a complete new end game scenario and throw out most of the actually good political scheming stuff that was mostly well written and made sense that came before.
Also just to mention, films don't take that long to shoot most often. THe biggest time waste is, building sets, planning, getting a crew together takes a while and hiring directors, actors, organising shooting schedules, working around filming on site, etc. A film might take 3-5 years to finish, but the shooting is only actually 3-6 months probably after 3 years, then post production then it gets released.
A tv series is a hugely different beast. Firstly you need to do all that, but mostly once. Most series like this are shot in a few locations that are generally bought/rented on the long term, the actors are long term, casting, preperation, sets, locations, etc, it's all somewhat of a one off thing at the start. Then it's way way easier.
If none of the actors have other work on you could pretty much make a 2nd and 3rd film with only a few months extra shooting per film. This is actually why the Hobbit, Lotr and lots of other trilogies end up being shot together because once everything is actually setup which takes an age, filming is relatively easy. Basically it doesn't take massively longer to film way more content than you get in a film at similar quality, the biggest pain in film making is planning and logistics, not the actual filming.
Also iirc, they film in several locations, have several filming crews and film a lot of stuff concurrently.