I think I like that Finn only has one song in this episode, a duet with Ryder (The Glee Project winner Blake Jenner). Monteith does have a good voice, but care must be taken to choose songs that really connect with him, and this isn't always the way he is handled on Glee. Luckily, the passing of the torch message in "Juke Box Hero" manages to satisfy both as a Finn melody and introduction to Ryder.
With the inclusion of Ryder, the second generation Glee core cast is complete, mirroring the original quartet at the center of the early seasons. Ryder is clearly the new Finn, Jake (Jacob Artist) easily steps in for Puck (Mark Salling), being his half-brother with a similar personality, Kitty (Becca Tobin) is a great Quinn (Dianna Agron) replacement, with a bit of Santana (Naya Rivera) tossed in for good measure, and Marley (Melissa Benoist) is the more relatable, hip version of Rachel (Lea Michelle). It may be a bit of a repeat, story-wise, but the characters are just different enough to still be enticing. Their tales shouldn't play out quite the same as their predecessors.
Which leaves Unique (Alex Newell) as the successor to Kurt (Chris Colfer). He won't be apart of the primary love triangles, but he is a fan favorite side character that draws enough attention to pull him into a status just as important as the others, even if that isn't the original intention. He (she?) also has enough of Mercedes' (Amber Riley) diva power to make another version of her unnecessary. Unique is easy to love, fantastic to root for, and his struggle with accepting himself, and earning the part of Rizzo in Grease, is both inspiring and moving.
On a side note, Unique's audition with Marley is a high point in this episode. "Blow Me (One Last Kiss)" is a great showcase for Unique's vocal strengths, and it also unexpectedly lets Marley out of her box a bit. She exhibits a side of her we have not seen before, and the growing friendship between Unique and Marley, as well as how they help each other, is Kurt and Rachel 2.0 in all of the best ways.