Agree completely w/ vividpsychosis. LE #315 arrived yesterday at my house (posted a few pics and thoughts in the official owner's thread, if anyone is interested). I don't play competitively/tournaments, but: consider myself a discerning flipper. And: either own or have owned Bally/Williams, JJP, Spooky, Data East, Heighway. And: have put serious play on every game on the top 100 (as a consultant, I <used to> travel every day. frequently stopped at the best pinball spots coast to coast). plus I built a high-end Virtual Pin. I know - it isn't the same thing. But: better than nothing. And: some of the original tables using PinUp Packs are something else (e.g. Harry Potter, Stranger Things, etc.).
ANYWAY, I am completely blown away by GNR. I was *slightly* concerned about gameplay after watching the initial streams. But: grail theme led to an impulse LE order at launch announcement (btw: direct from JJP website. must have been one of the first people to have order processed once you could actually purchase). First time I've bought a pin w/out putting it through its paces (hell: even had several trips to play Alien at SF's Flipper Room before pulling the trigger).
Anyone claiming this game doesn't have "flow" must have a different definition of "flow" than I do. you can absolutely hit orbits/inner loop/ramps for quick action. The light and sound show can be overwhelming on first play. But: the rules are clearly explained on the mini screen and through call-outs. But: WOW the experience. The risk/reward of continuing song mode vs. cashing out adds an awesome dynamic. The light and sound show is absolutely phenomenal, especially as you build momentum in a song.
My only quasi-negative: the Album wizard modes aren't fully fleshed out yet (i hope). They are technically there, but: honestly a bit of a letdown after the mind-melting of crushing a song like "Live and Let Die", earn an encore into the next song, then moving into "boss mode" animations with video-gamey-sound effects. Fully expecting those to get better as code matures (and: let's give props...most games ship with place-holders for wizard modes. GNR has a ton of them out of the box).
Upper playfield is better than Wizard of Oz, but: spiritual successor. most importantly: it does not interrupt the flow of the game like WOZ. I love that some shots can find their way directly to the Gibson headstock/ball lock. The VUK to the bass "string" paths is super cool. The diverter that changes the left ramp from quick turnaround to the upper playfield is also sweet as hell. Will withhold judgement until I get a chance to play a SE to have an opinion to have it changes shots/flow.
Beyond the "collect band members", "start song", "complete album" main mission path, there are a ton of other multi-ball opportunities. Spend a few minutes with the rule sheet on JJP and they go from mysterious to intentional. Can there be a lot going on? Absolutely. Part of the design. But: as stated: the single ball pressure to either start song or end song raises tensions quite a bit. And: as has been said, all multi-balls rules/setting can be fine-tuned to your liking. So far, I've only upped the flipper strengths a bit and turned on Adult mode (needed some "Mr. Brownstone", even with teenagers in the house).
Happy to answer questions as I have one sitting a few feet away. Hope everyone gets a chance to play this; your mileage may vary, but: I'm absolutely thrilled. truly an incredible pinball experience (which: even my wife and teenage girls LOVED, which never happens).