I thought it was an Awesome episode, and a great ending to the season. I thought it had some good emotional points and still maintained the level of fun throughout the series. Jack's probably was changed, but Christopher Ecclestone's ending wasn't tacked on or changed...it was revealed that he'd only been signed for a single season, and they knew that from the very beginning. The only thing that went wrong was that the BBC wasn't supposed to reveal that information so early. Which is a pity, as I really liked Christopher Ecclestone...but I'll give Trenant the chance to win me over. His one minute in 'Parting' was a good start.
As for humanity in the 14,000 year...remember that this is Dr. Who, for a start: projecting realistic futuristic or alien civilazations has never been a strong point, or even a goal. Of course, if you follow Dr. Who continuity, then the Earth has been through a LOT. Conquered several times, abandoned during the Solar Flares problem, subjugated repeatedly....it's a wonder mankind got anywhere at all, frankly.
The Daleks were redesigned, btw, just incrementally. The basic design is the same, but the middle swivel part was new, iirc. The chain WAS silly.
If there is a quibble to be had, it's the same one that I've had throughout the show, which is that understanding the Time War is kind of confusing. Did the Daleks all travel from every point in time to the final battle, or what? Mind you, if the Emperor Dalek managed to escape, then that opens the door for others to have escaped, including other Time Lords.