I'm not sure entirely why this is, but this episode felt a bit unfocused to me. I liked almost everything about it on the level of humor and basic story, but I think a lot of the pieces just didn't click the way I would have liked. On top of that, there were some really overused tropes. Let's take a look.
The main plot of the episode involves Sheldon making an important scientific discovery, which leads to a new element being synthesized. This is amazing scientific news, of course, but Sheldon then realizes that it only happened because he made a lucky mistake. He now doesn't feel like he deserves the praise, and he gets mad when everyone tries to make him feel better. Amy doesn't try to spare Sheldon's feelings. She says that she thinks his mistake was very bad, and that he isn't deserving of any praise. Sheldon says that this is the most romantic thing he has ever heard.
At the end of the episode, Amy imagines what it would be like for Sheldon to kiss her, but then is sadly pulled back to reality. In typing this summary, I realized my big problem with the episode. Ostensibly, the theme that ties everything together is the romance, right? The other two plots (Leonard/Penny, Howard/Bernadette) center around the way these couples express their love for one another. But Amy and Sheldon don't really have a romance plot of their own. Instead, you have Sheldon's scientific breakthrough and then freak out. There's an episode tag dealing with Amy and Sheldon's relationship, but really the Sheldon plot with his discovery seems like it belongs in an entirely different episode!
But anyways, in the interest if brevity I'll move on.
Penny realizes that she's no good at being romantic with Leonard, particularly since she's never had to try very hard in relationships before. Since she's beautiful, guys just throw themselves at her. She decides to try and do something sweet for Leonard, and gets him a first edition copy of Hitchhiker's Guide to the Galaxy. The only problem is, Leonard already has it - and Penny had been there when he bought it, no less. Penny is mortified. She says that Leonard is too romantic and good to her, and then pulls out a box full of mementos from their relationship to prove her inadequacy compared to him. Predictably, Leonard is touched by this gesture, and all is well.
While not original or particularly creative, I liked seeing these sweet and simple moments between Leonard and Penny.
Then there's the best part of the episode. Howard wants to write a song for Bernadette to celebrate the anniversary of their first date, and he enlists the rest of the friends to help. There were a lot of reasons to love this plot. My parents also still celebrate their dating anniversary, so it was cute to see that there. I also loved that things don't go exactly to plan, but they don't get all ruined either. Bernadette ends up in quarantine because of an accident at work, so Howard has to bring his surprise to her.
A small nitpick - earlier on, Howard was asking his friends to play different instruments for the song, but in the end they ended up serving only as backup singers, so that sort of confused me. But yeah, that's just a detail.
The song itself was adorable. It was dorky, and science-y, but so genuine and so sweet. Howard was in fine form, and Bernadette started crying, which was just so perfect. I also loved this moment because it acknowledged how much the entire group cares about Bernadette. Oddly, for such a great character, she sometimes gets put on the back burner. In this story, she really gets to shine, and everyone gets to show their appreciation for her.
So, there you have it. I already mentioned my one big problem from this episode: Sheldon's science story just doesn't mesh with the texture of the other stories. There were also some smaller problems, like the cheesy thing with Penny and the box of mementos. But overall, I think this was a cute episode. That song from Howard was enough to keep me smiling for quite some time.