“Hello, suckers!” Sue Sylvester chastised (from her perch on the video screens) as the lights came down for the final L.A. performance of “Glee Live” Saturday night. Similar sentiments no doubt abound among music purists who have spent the last year agog over the elevation to full-fledged Cultural Phenomenon of a show that, admittedly, features a vaguely Up With People musical aesthetic. Yet among the 6,000 devotees who packed the Gibson Amphitheatre for the fourth time over three days, few emerged feeling that they had been taken – after all, no matter how much we might one day regret having fallen so hard for Glee, it certainly has inspired rabid devotion on an increasingly international level. It also has, in many senses, provided something of a public service: Who can really argue with a show that simultaneously has revived popular interest in arts education, has gotten a new generation hooked on musical theater, and has rendered “Don’t Stop Believin’” not merely hip (thanks, Sopranos) but relevant to the tween multitudes?

The Journey classic provided Glee’s seminal moment, and it served, fittingly, as an enthusiasm-goosing opener for the cast’s concert of favorite tunes from the series. (The band apparently has a future on the show as well: “Faithfully” will be performed during the season finale next week, and the Glee kids tore through a mashup of “Any Way You Want It” and “Lovin’, Touchin’, Squeezin’” near the end of Saturday’s performance.) Following its out-of-the-gate high point, “Glee Live” settled into a rather predictable selection of show highlights, bouncing from “My Life Would Suck Without You” to “Push It” to “Sweet Caroline” to “The Boy is Mine” to “The Lady is a Tramp” with little concern for genre barriers (or, in too many cases, the Wonder-bread quality of the arrangements and vocals – though at least there was no lip-syncing in evidence, except perhaps on the crazy-costumed tribute to Lady Gaga’s “Bad Romance”).

Throughout, the cast members performed their glorified karaoke while remaining in character – leading this jaded observer to wonder, more than once, how tens of thousands of fans could have been hoodwinked into attending Brady Kids concerts back in the 1970s. (Have there been other instances when a TV-series cast toured in character? I can’t think of one — apart from the Monkees, sorta.) As much of an in-the-moment blast as it is for a Glee fan to watch Rachel and Finn and Puck and Quinn and Mercedes and Kurt perform onstage, the euphoria was tempered by the nagging sense that there’s not much difference between watching wheelchair-bound Artie (played by the not-paralyzed-in-real-life Kevin McHale) spin around to his god-awful version of “Dancing With Myself,” and a kid of the ’70s watching Christopher Knight-as-Peter Brady sing that paean to adolescent vocal cords, “Time to Change.” With their occasional video-screen commentaries, adult Glee stars Matthew Morrison and Jane Lynch even seemed like a latter-day Mike and Carol coupling … well, perhaps with Sue Sylvester as the anti-Carol.

Clearly “Glee Live,” like those old Brady Kids concerts, is not a gig you’d want to wander into without an established affection for the series – except for the opportunity it offers to witness the brilliance of Lea Michele. Already a Drama Desk-nominated Broadway actress (Les Miserables, Spring Awakening) before she took on the role of Rachel Berry – and currently one of the world’s 100 Most Influential People, according to Time — Michele is by far the most seasoned stage performer of the Glee actor/singers, not to mention the most talented (by a long shot). So it’s no surprise that she dominated the proceedings Saturday night, and provided both of the concert’s emotional peaks with her renditions of the Funny Girl chestnut “Don’t Rain on My Parade” and the glorious “Defying Gravity,” from Wicked.

She sang the latter song as a duet with the otherwise-underused Chris Colfer (Kurt), and its impact onstage was easily as poignant as its use on the series. (Fun fact for Glee fans: Colfer’s real-life high school banned him from performing “Defying Gravity” in a talent show because it’s usually sung by girls.) Their joint effort moved Michele to (real) tears by the end of the song; whether she was overcome by the beauty of the performance, or overwhelmed by the impact the Glee experience has had on her own career, the emotion wasn’t difficult to understand. One thing’s for sure: Michele is a Streisand-level superstar in the making – if it’s possible to attain superstardom based solely on talent in this day and age. Sad as it is to say, she may need to become tabloid fodder if she wants to take it to the next level; hopefully she’s got Lindsay Lohan’s number on her speed dial.

Apart from Michele’s diva turns, the highlights of the wildly uneven (just like the series) “Glee Live” were ones you’d easily guess if you’re a regular viewer: Amber Riley’s (Mercedes) soulful renderings of “Beautiful” and “Bust Your Windows,” the mattress-trampoline set piece for Van Halen’s “Jump,” the vivacious performance of Amy Winehouse’s “Rehab” by rival group Vocal Adrenaline (still reveling in the impropriety of the song choice), and the encore-closing “Somebody to Love.” All told, the concert builds upon Glee’s high-concept foundation (High School Musical meets Mamma Mia meets American Idol) — and the robust sales and rapturous receptions that so far have greeted this brief, four-city tour are likely to burnish even further the show’s stature as a cultural touchstone. It’s a ride we Gleeks had better enjoy while it lasts, because we’re all headed for a major guilt hangover sooner or later.