Here's the full scene in question (Spoilers obviously):
[ame="http://www.youtube.com/watch?v=GrwN5jS4bt4"]Ridley[/ame]
The arguement is kind of devalued as right after, Samus immediately starts walloping Ridley and then goes up to him and overcharges a blast directly into his mouth, while he's downed I might add. [hide]Ridley escapes, being badly burnt and all, essentially having to run away the second he got a chance. (He does end up "petrifying" though later, due to the final boss.)[/hide]
And even that isn't putting into full context as there is more before and after this particular scene in the game after all; just because she begins to let her "guard" down, briefly, and has an emotional response, doesn't mean she's a "wimp" throughout the entire game and thus "her character has been ruined forever".
In short what happens here is (using the video alone):
[HIDE]
-Samus and Anthony enter the room
-Ridley suddenly appears and slowly rises up from the flames somewhat demonically
-This triggers a flashback to her childhood when Ridley and the Space Pirates came and killed her parents and the rest of the colony, not to mention surprise at the fact Ridley is still alive after the explosion of an entire planet (which was "recent" according to the prologue of the game), thus causing her to lose her focus and start to panic slighly.
-Adam watching, and also afraid for Samus and Anthony's safety, tries to get her to snap out of it to no-avail.
-Samus eventually breaks out of it just when Ridley grabs her and, despite her attempts to get out of his grip, including trying to straight out punch him, her mercilessly scrapes her on the surrounding walls causing her armour to become severely damaged and begin to lose cohesion.
-Anthony tries to get Ridley's attention by yelling and shooting at him, causing Ridley to try to dodge and allowing Samus to be able to escape and reinitalize her armour just before hitting the ground, hard.
-Anthony eggs on Ridley, filled with bravado and wanting to protect his friend while she's been downed, and tries to take him out on his own, quite possibly intending to sacrifice himself to do so, considering he overcharged his blaster rifle to critical.
-Samus weakly tries to warn Anthony to stop and essentially stayout of the battle.
-Ridley comes up and knocks Anthony with his tail into the nearby lava before he can get off another shot, with Samus prevented from saving him in-time.
-Enraged and fully focused, Samus goes directly for Ridley, as he comes to confront her again.
-Battle ensues, with Samus hitting hard against Ridley and dodging various attacks, including even shooting him directly when he's downed.
-Eventually Ridley collapses in a heap.
-Samus silently approaches the body and, satisfied, goes over to Anthony's blaster possibly to mourn or at least take it with her and leave, and then likely contacting Adam to inform or discuss events.
-Ridley gets up one last time in a surprise attack. Quickly, Samus reacts and shoots multiple shots at Ridley, just barely missing him, but enough to drive him off.
-The shots make a hole in the wall, Ridley then hightails it out of there, finally leaving Samus alone to herself and the few remains of what was once one of her only close "friends" in "recent" memory. I'm also relatively sure by this point she and Adam are the last ones out there of what was once a seven person team.[/HIDE]
I've been following what playthroughs I can find, and although having not seen everything, despite there being a bit too much introspection (mainly that it's bordering on a bit lengthy at points), nothing seems so far too out of place. One of the points of the game was to "show the real Samus," essentially to humanize her and thus show the actual emotions and influences tied to her actions. Mainly it seems like everyone is up in arms with Samus simply not being as overtly "cold," "stoic," and "devoid of emotion," bordering on "cyborg-like", as people might have fantasized, possibly deriving a "cold-killer" persona due to her occupation and her lack of speech in most of the games (particularly the early ones).
Considering her backstory, alot of what I've seen here makes sense. We haven't seen much of it as there has been so little opportunity used to actually examine it from her perspective or her interactions with others, as the games often have little to no dialouge (inner or outer) after all; she's still the courageous, determined, loner we've known, but she is still essentially human with traumatic elements in her past that play a part in developing her as well. These include being somewhat socially detached/inept and intropsective and alienated from most humans due to her background, loss of parents (and thus possibly lost elements of childhood) due to the Space Pirates and thus combined fear and anger towards them (especially Ridley), her experiences and relationships with Adam, Anthony, and the rest of the Galactic Federation Army, her maternal experiences with the Baby Metroid and its demise (which were "recent" at the start of the game), her experiences with wiping out the Metroids and the Space Pirates and thus surprise and frustration at their constant survival from increasingly impossible situations, and considering by this point it having been essentially twice over (thrice if you consider the Metroids alone), it's probably beginning to wear on her a bit, etc. Really all this did was explore these a bit more and give them a proper "voice."
Would you have preferred her instead act like Seven of Nine (and even they tried to humanize and explore her past as well)?