
It'd been a while since Shannon was given something to do, so after she sees an apparition of Walt in Sayid's Love Shack she embarks on a quest to find him. Cue the parallel to the flashbacks, where Shannon's again coping with a recent death (her father) and discovering that nobody believes in her.
Poor Maggie. If only they'd given her character something even remotely redemptive beyond looking after Vincent. Even in the wake of her father's death, her vision was mostly limited to the tip of her nose. She loved her father, no doubt, but her objective soon became clear: get the money from his will and move to New York.
Boone's mother Sabrina was presented as the cold-hearted villain in the episode, yet when I really break things down I can't say my views were all that different from hers. Shannon never could get past her entitlement mentality, so regardless of whether her father reserved money in her name it WAS a better idea for her to be self-sufficient for once.
Anyway, Elizabeth Sarnoff did a nice job of bringing this episode to its climax, with the Tailies cutting through the jungle to shave off some time (in hopes of saving Sawyer) and Shannon chasing after visions of Walt. Even though I was following both storylines closely I wasn't expecting a gunshot, and certainly wasn't expecting it to be Ana Lucia. It's almost a poetic turn of events, given that Shannon was almost begging for someone to put her out of her misery.
Bonus points for planting the seeds on the Charlie angle, with him developing a slightly creepy affinity for Aaron.
Not to nitpick but I must deduct points for the ridiculously sturdy and complex stretcher that Michael and Eko built in such a short time. There's no way that should've made it through the writers' vetting process.

It was good to see Maggie Grace get a proper sendoff, even if she was still very limited in the script in terms of emotional scope. I would've liked to have seen a glimpse of a happier time in her life — other than the perpetually awkward game of House with Sayid.
Even though I couldn't really sympathize with Shannon at any stage of her arc, Grace still played the role very well and was certainly convincing in her final moments. She was a broken, lonely woman who was exhausted from even trying. Grace came very close to making me sorry to see her go.
Deductions for Michelle Rodriguez's performance, and not just because Ana Lucia's personality is like nails on a chalkboard. Rodriguez has an annoying habit of over-enunciating and over-hamming some of her lines, the most obvious case in Abandoned being:
ANA: They took THREE of us... nothing happened for TWO [teeth gnashing] WEEKS... then they came back [more gnashing]... they took NINE [inexplicable pause] MORE.
Ugh.
No memorable performances for the rest of the guest or main cast, positive or negative.

The highlight of the directing was the final scene with Sayid and Shannon in the pouring rain. I loved the way that whole scene unfolded and the delayed reveal of Ana Lucia. The shot of a lifeless Shannon in Sayid's arms was a pretty powerful way to close the episode as well.
Deductions for a terrible moment of CGI when Ana Lucia's group is at the rocky shoreline. Eko suggests cutting inland, Ana Lucia looks to her right at the most obvious overlay of CGI jungle you'll ever see on LOST.
More deductions for the stretcher (I know I'm harping on this too much), which might have been a better sell if it hadn't been so perfectly constructed. Michael's good but he ain't a miracle worker. A much more crude design would've helped.

At the risk of being redundant, had we gotten a glimpse of a kinder, softer Shannon this episode would have a lot more replay value. I try my best not to celebrate the departure of a character but I came pretty close here. You'll find plenty in the LOST community who didn't hesitate to pop the champagne.
But as it stands, Abandoned covers the Tailies' tense journey through the jungle and Shannon's bitter life leading up to the Oceanic crash. Not exactly the stuff I'm anxious to replay repeatedly.
However, given the impact this would ultimately have on Sayid, and since it's an original Lostie passing away, there is undeniable importance behind some of the episode's events.

The bulk of the atmosphere lies in the Tailies' expedition and the closing scene, with a few little tidbits with Charlie, Claire, and Locke along the way. Other than that the flashbacks played a little closer to a soap opera than I would've liked.
There were certainly a few scenes that were designed to be emotional but they never resonated with me. Shannon at Boone's grave, Shannon getting shot, Sawyer teetering on the brink of death from a bullet wound... none of them had me reaching for the Kleenex.
While I was sorry to see Maggie's assignment end, I found myself reciting what Boone said in Hearts and Minds. I felt... relieved. Relieved that I'd never have to see post-sex Shannon and Sayid ever again.