Let's get past the obvious here: Jensen's face was unreal.
Now onto the angst: This is the first time Sam's really happy in however long? Seriously? I don't believe that A) it's the first time that everything feels good and B) he really means it. I think A) the writers are just manipulating Dean/us and B) he was likely way more happy in earlier years ... or hell, even back when he was at Stanford* and didn't have to worry about hunting and heaven and hell, not to mention the continuous guilt over letting Lucifer out (which I think was a really odd and stupid point to make four years later).
*I almost typed Stamford and thought of The Office, and wondered if that's just as bad as hell.
In the last 10 minutes, I started to make arguments for why Sam would be happier in the early seasons of the show ... but then got pretty sad. I mean this is what his life looks like:
Season 1
Pros: He gets to know his brother again, has a purpose - to avenge Jess and Mom's deaths
Cons: Jess is dead, he's sucked back into hunting, and his father goes missing. He also starts a trend of trusting the wrong woman at the wrong time (hi Meg!)
Season 2
Pros: He's with his brother, gets laid, goes to Hollywood.
Cons: Dad is dead, Dean lies to him over what their Dad wanted, thinks he's a monster, is betrayed by another monster!lady and has to put her down, dies and comes back potentially changed, finds out his brother sold his soul. Oh, and goes to prison.
Season 3
Pros: They've killed Azazel, still hangs out with his brother, has a purpose - to save Dean, survives Lilith.
Cons: is hunted by superhuntervamp!Gordon, has the worst day ever - repeatedly, can't save Dean, watches him die. Oh, and goes to jail, again.
Season 4
Pros: Gets Dean back, has super demon!killing powers, gets laid a lot with Ruby, hooks up with Dr. Cara (!!!), visits pretty black and white Oktoberfest, has a purpose - killing Lilith, kills Ruby.
Cons: Keeps secrets from Dean, ruins their entire relationship, again falls for the bad lady, drinks demon blood, has to go through massive withdrawals and terrifying hallucinations, nearly kills Dean over a siren, releases Lucifer.
Season 5
Pros: has a purpose - kill Lucifer, somehow makes up with Dean, pretty much saves the world.
Cons: EXTREME GUILT, Meg returns, Lucifer is out, the Four Horsemen are loose, is possessed by Lucifer, goes to hell.
Season 6
Pros: Returns from Hell, finds more family, gets his soul back.
Cons: Returns from Hell more fucked up than ever.
Season 7
Pros: Gets married, runs into old friend Amy and lets her go.
Cons: Gets married, Dean kills old friend Amy and he can (again) no longer trust Dean. Oh, and has lucid hallucinations about Lucifer and being back in hell and ends up in a psych hospital.
Season 8
Pros: Gets laid, has a purpose - completing the trials and locking the doors of hell forever.
Cons: Lives with Amelia, doesn't look for Dean and is guilted over it forever, goes crazy/weak over the trials.
Season 9
Pros: Still alive, somehow. Very happy with his life for the first time in a very long time.
Cons: Is (once again) inhabited by another being without his knowledge, and (once again) is being lied to by Dean.
I guess he could say that as far as he's aware, this cons list is pretty short compared to past seasons.
Poor Sam.