If TFA was a safe almost-retread of A New Hope, you would think you'd be safe in assuming that this movie would be a retread of The Empire Strikes Back.
For better or worse (depending on what you think of the movie), The Last Jedi is not a retread of any of the previous movies, and it's easily the 'riskiest' Star Wars movie to date.
The movie has three storylines:
For most of the movie these plotlnes are separate, with some mingling in between before they naturally all collide at the end.
At this point, if you haven't seen the movie, you've probably heard that it's dividing audiences. I think it's a fair assessment to say this is a very 'marmite' Star Wars. You're either going to love what they've done, or you're going to hate it.
I don't want to spoil anything, so I'll wrap up in saying all the cast are solid, the music is great, special effects are top-notch. It's the story that's causing so much debate.
Go see it.