
There are two certainties in the world of LOST: 1) Sayid-centrics are going to have dark and violent moments, and 2) all groups bring sandwiches to their captives.
Flashbacks show Sayid executing the last man on Ben's long list of Widmore operatives. When Sayid learns his work is done, he's completely lost with no idea what to do next. Ben would leverage that uncertainty in a later flashback, setting up the Sayid/Hurley scenes at Santa Rosa in early Season 5.
On the island in 1977, Sayid is held prisoner by the DHARMA Initiative and he ain't talking. Sawyer conjures up an M.O. for him — defection from the Hostiles — but Sayid won't play along. Even after Oldham (the resident DI torturer) makes him spew a stream of crazy truths, Sayid proves to be uncooperative.
Radzinsky finally gets his way, swaying the DI to vote for Sayid's execution. Thinking Sayid's a Hostile, young Ben creates a diversion to bail him out in the nick of time. This is where the "dark and violent moment" comes in — Sayid repays the favor by shooting young Ben in the chest and running off into the woods.
That last moment was quite shocking for me, even after witnessing the execution of Alex in Season 4. With all the child-killing going around I was half-expecting Aaron to take a bullet to complete the trifecta. That's not to say I thought Ben was really dead; I was about 90% sure we'd see him live another day. But this is LOST we're talking about, so there was beauty in the fact that there was even 10% doubt.
He's Our You isn't my favorite Sayid-centric but it certainly adds depth and intrigue to his character. The same cannot be said for a few centrics earlier in S5, which only briefly covered the characters they were dedicated to (for better or worse).
Bonus points for having Ben hand Sayid a book entitled "A Separate Reality." Yet another case of a very early seed being planted for the audience.

This is Sayid as Sayid should be — a cold-blooded, unpredictable assassin who won't be denied his goals. Naveen really shines when this is the scope of his character. Of course we also have a brief non-fling with Ilana but Naveen doesn't ham it up this time around.
He finally got to do something a little different — the interrogation scene with Oldham. It was fun to watch a drugged-up Sayid spill his guts (figuratively) and have a few laughs while he was at it. Well played by Naveen.
Holloway's featured quite a bit in this episode and he had some fine moments. His exchanges with Sayid in the holding cell were great for a number of reasons (more on that in a bit); I especially loved his "what the hell?" reaction to the burning DHARMA van.
I'm lukewarm when it comes to Zuleikha Robinson, otherwise known as Ilana. In some ways she's very similar to Naveen, effective when she's playing a badass but slightly disturbing when she's acting like a seductress. In the near future she'll get a mixture of praise and criticism from yours truly, but as far as He's Our You I'd say she broke even.
The DI cast all did pretty well, especially Sterling Beaumon (young Ben). I couldn't believe I found myself sympathizing for young Ben when his father slammed him against the bars of Sayid's cell, but that's what good acting will do.

This was the third and final directorial effort for Greg Yaitanes; coincidentally he also directed another episode where Sayid was held captive ("Solitary").
He's Our You was visually smooth throughout, whether it was a flashback from Tikrit or Sayid's "shot heard 'round the world" to end the episode. The set design for Moscow was brilliant (no surprise there), but more importantly the scene where Sayid chases down the operative is frantic and intense.
The most impressive directorial sequence is the burning DHARMA van smashing into one of the houses. The visual alone was enjoyable but it was augmented by the controlled chaos that followed.

I'd put this episode in the same category as Namaste and a couple others in Season 5 — smooth, interesting episodes that are enjoyable to watch but very plot-driven. Plot's obviously important but character-driven episodes tend to resonate more with me over the long haul. He's Our You didn't exactly cover a lot of new ground with Sayid in terms of his internal struggles.
It's significant that Ben would spring Sayid loose and suffer a serious wound — one which would ultimately lead to him becoming an Other. Beyond that, the events of He's Our You were links in a chain of events leading to the Losties' eventual showdown with the DHARMA Initiative.

Again, plot-driven episodes generally lack the kind of atmosphere you'd find in character studies such as, say, Deus Ex Maxhina. However there were a few moments in He's Our You which evoked a bit of nostalgia if nothing else. I'm mostly referring to the face-off between Sayid and Sawyer in the holding cell. As I was watching those scenes I couldn't help but think to myself, "We've come a long way from their fist fights on the beach."
In terms of emotional impact, there was certainly an element of shock at the very end. Most of the shock was that they'd show it on network TV, not so much the possibility that Sayid somehow changed the past.