Oh, loads of interesting comments on this thread. My two-pennorth for what it's worth (well, 2p, I guess...)
It was fun as a Saturday afternoon with popcorn. Some great moments (Holdo crashing the ship through the destroyer at light speed). But lots of flaws.
Top of my list would be: it felt like they'd come up with half a dozen possible "fantastic show-piece climax endings", couldn't decide which one was best, so threw the whole damn lot in there one after another (the fight between Rey and Ren, Finn sees off Phasma, Holdo saves the remnant of the rebels, Finn looks like he's going on the brave suicide attack, Luke and the showdown with Ren... too much already!)
It also felt (totally unnecessary side plot with Finn and Rose) like they were writing for a TV series, not a film. Too many minor-ish characters, which in a TV series you would have had time to develop their characters, just thrown in to make a mush. On the subject of Finn and Rose - Finn has been doing this almost-running-away-then-getting-cornered-into-doing-the-decent-thing schtick for 1 1/2 films worth now. Dear writers - if you wanted me to start warming to him as a character, don't you think the scene would have been massively stronger if you'd had him get to the escape pods, have a moment of epiphany and find the strength to say "this time I stand my ground and stick with my friends" on his own? Double advantage: Finn would have genuinely grown as a character and we could have left the boring casino world (and gratuitous cute kids) on the cutting room floor.
Actually, both the sequential climaxes that turn out to be mere foothills and the casino-can-we-get-the-codes-in-time dead end are illustrative of the basic problem - it was plotted like a TV series, not a film. Films need much tighter plotting, much more of a sense of going somewhere (by which I mean the sense that they might, that it's building to something - not that we as an audience have to know what the destination is).
Darth Kevin the Teenager grew on me a bit, but at the same time I realised what was so wrong with his character. I've been toying with the idea of tragedy. Classical Greek tragedy - you get an otherwise great, heroic figure who becomes the toy of the gods and gets destroyed by their heroism just being the wrong thing in the wrong place at the wrong time. Shakespearean tragedy - you get an otherwise great, heroic figure who gets destroyed by their own character flaw - MacBeth's ambition, Othello's jealousy, Lear's narcissism. Kylo Ren doesn't cut it in the "otherwise great and heroic" stakes, and his character flaw appears to be... indecision! "OMG, I can't decide if I love or hate my father... OMG, I can't decide if I admire or hate Snoke, my mentor... OMG, I can't decide whether I despise this upstart girl or want her to rule the galaxy by my side..." Come on, writers, that is not the stuff that great sweeping epics are made of.
(In fairness, though, young Luke was pretty whingey too!)