A quick review of last night's "30 Rock" coming up just as soon as my yak has smallpox...

Of the many recurring characters "30 Rock" has introduced over the years, none makes me quite as happy to see as Dennis Duffy. Other characters may be crazier (Dr. Spaceman), or have sillier names (Dr. Spaceman again), but Dennis remains a perfect foil for Liz, because he's ridiculous enough to be funny (his new business involves burning DVDs onto laserdisc) and yet just real enough that you believe that Liz dated him once upon a time, and that she's still capable of being sucked back into his cheeseball life. Dean Winters(*) always embraces the obliviousness — I liked the reveal that the "lez movie" he was so excited to watch was "The Kids Are All Right" — and bringing Dennis in allowed the show to move Liz and Criss' relationship forward. I fear that eventually James Marsden will have to go away in the same way that Jon Hamm, Matt Damon, Jason Sudeikis, etc. have had to in the past (hence Liz never having a relationship last more than 9 months), but Liz's "I love you" in the midst of all the caricatured Irish-American tomfoolery of St. Patrick's Day was a funny, sweet moment. ("Is now the time on St. Patrick's Day when we talk about our feelings?") If you can't say "I love you" while wearing Hulk fists, when can you?

(*) I know Dennis has made a number of appearances on the show since Winters started playing Mayhem in those Allstate ads, but last night felt like the first time where NBC presented more than one of them during an episode where he was a guest star. I like how both Dennis and Mayhem are these malevolent, destructive forces, though Mayhem is much more self-aware.   

The other stories were more of a mixed bag. Tracy and Jenna's jealousy of each other has never been among their more entertaining traits. And dressing that old conflict up as an example of Hazel's learning curve just wound up dragging Kenneth back into page business, when I was looking forward to him being done with that.

Jack getting sucked into a role-playing game with the writers at least gave us the homage to the "Game of Thrones" opening credits(**), but felt a little slight overall, rehashing Jack's feelings about Kabletown without doing much new with them. (Unless he decides to start selling glass in the real world, as well.)

(**) Though it wasn't as great as either the recent "Simpsons" main titles or the kids in the cast singing the theme. We may have already reached oversaturation on clockwork riffs.

Still, Liz/Criss/Dennis and all the over-the-top St. Patrick's Day stuff was enough to carry the half-hour.

What did everybody else think?