My gut reaction upon exiting the cinema... Disappointed.
My answer after a day or so... I'm going to have to see it again.
* SPOILERS AHEAD *
The Last Jedi has some neat things going for it and is rammed full of ideas (maybe to many). I particularly liked the way Rey and Kylo's characters develop through the length of the film. There is a strong emphasis that the two central antagonists are effectively cut from the same cloth. The fact that either is of the light or the dark is purely down to the choices they have made along the way, with their innate power emphasising the impact of these choices but not actually defining them. Interestingly the film moves hard to remove the force as an excuse for either of these characters actions. The revelation of Rey's parentage (and Luke's failure as a teacher) effectively leaves her as a free agent who sits on a knife edge as her emotions ebb back and forth. Conversely Kylo, after rejecting Luke's training and the teachings of the light almost goes as far as doing the same with Snoke and the teachings of the dark in the latter stages of the film. As a result I genuinely have no clue how things will play out in part three, which is actually a rarity in this series. The lack of strict black or white morality in The Last Jedi is a real breath of fresh air, if not more than a bit disconcerting given what we've come to expect from these films.
That being said this film has huge problems. It is over long (there are entire scenes that lead nowhere and add nothing to our understanding of characters or the story), massively unfocused (Snoke is never explored in any detail and killed off before his impact can be explained, while Finn may as well have not appeared in the film at all, his story being almost completely inconsequential), and at times almost felt like an SNL parody rather than the next instalment in the franchise (flying Leia, _that_ moment with Luke and the lightsaber, not to mention the core conceit of the story being a slow motion chase straight out of Spaceballs).
It's a real Marmite film and I can see why it is splitting opinions so thoroughly. I'm not quite ready to say that this makes it a bad film, however it was definitely not what I was expecting (and not wholly in a good way) and didn't leave me with the high I was looking for and IMO all of the bast Star Wars films achieve. For me Star Wars has always been as much about the tone of the story telling as much as any of the specifics of the world being depicted, and on that front this film is resolutely trying to do something very different and as a result left me feeling somewhat unsatisfied.