I'm going to offer what's probably an unpopular, incredibly niche bit of criticism. At the outset, I liked the concept very much. The story delivers on deaf representation quite well, on many different levels. Some of the tunes were great earworms. (The Bastards song is still stuck in my head.) Erin Weaver's King is hilarious (I loved her in Into the Woods @ Signature VA). Johnny Link delivers a very earnest portrayal of the title character. (Leanne Antonio was out, and Emily Steinhardt was her cover.) Jake Loewenthal is staying booked and blessed.
But there were a few elements that made it really difficult for me to step into this world. First, the accents were all over the place. I think I heard some variations of generic Scottish, Irish, American, and English -- sometimes from the same actor. Erin Weaver came the closest to staying consistent. I think they were shooting for a South Wales/Valleys accent, but the accent came across as grating and one-dimensional. Perhaps some do find a Valleys accent grating and one-dimensional. But my problem was that, to the extent that an actor attempted a Welsh accent, everything was said in exactly the same cadence and intonation. (I'm not Welsh, but know quite a few Welsh folks from both the north and the south of Wales, and their manner of speaking has a more musical and a fluid quality than what I heard at Signature last night.)
On a similar note, some of the melodies felt more Irish and Scottish than Welsh. (Cue joke about "What is Welsh music?") This is the same regiment that fought at Roark's Drift about 30-40 years before WWI. Their song is Men of Harlech, a military march made famous by Zulu, which portrayed the events at Roark's Drift. I wanted to hear some of that tradition in the music, instead of generic "oh, they're all Celtic in some way right?" music.
(As an aside, I'm pretty sure a good number of the regiment's members were English, not Welsh. They could've used that to get away with a few varied accents.)
The book also felt underdeveloped. Given that there's a war crime or two depicted in the musical, it'd be nice to know how things reached that point.
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Shooting a soldier who's surrendered is a war crime. "They took my friend and I shall have my revenge" seemed to come out of nowhere, and also went nowhere.
And while I understand the plot role that the nurse (Gwenolyn) plays at the beginning of the show, I think there could've been a better way to drive home the same point.
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Like West Side Story and a whole host of other musicals, the protagonist became enamored with a potential love interest in all of about 30 seconds. The author took the trope and added a somewhat clever turn. Where they (Gwenolyn and Private Jones) ultimately ended up made sense, sort of -- the perception of Gwenolyn's affection for Gomer was all a fantasy, as Gwenolyn's husband points out in the penultimate song (Fantasy, I think it was called). But the foundation on which the premise was built was pretty flimsy. At no point did I believe that Gomer actually cared about, or even infatuated with, Gwenolyn, except when she was a plot device convenient for him to do X and Y.
Why not do something more with the mistaken notion that military glory will help make Private Jones feel less "othered"? They allude to that at the beginning -- about why Gomer wants to shoot for king (the dude with the crown, not the best character in the musical) and country. At the end, Edmund makes the rather banal point of "You don't need her love, everyone who died for you loved you." But that works just as well with the notion that military titles and honours aren't what give rise to respect and glory -- it's camaraderie and the willingness of others to sacrifice that makes you rise above.
Not every musical needs a love story, even if the love story is more of a fake-out.
There were also a handful of moments where the dialogue sounded more modern American, instead of something a bunch of 1910s Welshmen would say. But all that is fixable.
Folks in the audience really seemed to enjoy the show, so I'm probably in the (very small) minority of folks who did not like Private Jones in its current form. And that's not to say I won't ever like it -- I think with some reworking of the story, and some tightening for consistency, this can be an excellent musical. I'll also offer up another blazing hot take in saying that this is more ready for prime-time than Swept Away.