I compiled several available reviews in the net. Some are recent, some were from earlier this year during Sundance. Enjoy!
Stewart holds her own with Gandolfini and Leo once again proving when she’s outside of the Twilight universe, she’s capable of so much more. thefilmstage October 24, 2010.
But while the pacing often sags, Stewart and her radical transition along with impressively expanding range from Twilight's moping teen to abrasive, profoundly damaged rude womanchild, effectively picks up the slack. As she settles into a sleazy routine that seems just as relaxed hanging around infatuated vampires, as glued to stripper poles and pasties. Though a testosterone stifled Gandolfini appears somewhat less comfortable in his own extreme switchup from wise guy to relative wimp, and assigned here to deferring to Stewart as the no-nonsense sassy chick in charge. Newsblaze.com October 23, 2010
Next comes Stewart, whom I love to hate. I’m not sure why. But this is the first film that I’ve seen her in where I felt like she wasn’t playing herself. She really made an impression and if this is the sort of stuff we can expect out of her, I’ll soon be a fan. WeGotThisCovered
...we did not expect much of Kristen Stewart, in [the] excellent 'Into the Wild' or 'Runaways', but too dull in the Twilight trilogy. And she proves it here with some talent - even if it's hard to let go of her angry teenager look - she [can] easily negotiate the rest of her career once the Vampire Saga has ended and been forgotten.
And the surprise is, well, Kristen Stewart as a young adult prostitute who finally breaks her romantic image [of silly]. Good choice.Filmosphere
But the film belongs to Kristen Stewart, raw, uncompromising, magnificent at every turn, delivering a ferocious and emotionally-charged performance. “Welcome to the Rileys” is a tough, challenging work, one that takes its time in exploring the fragility of human behaviour. It is a haunting, beautiful work with a masterful performance by Stewart at its heart.moviehole
Kristen Stewart here is tougher even than her punk rocker in "The Runaways." Who knew she had these notes? I'm discovering an important new actress.Roger Ebert, The SunTimes
As for Stewart, she’s okay. She does what’s required of her, which isn’t much of a stretch from her typical moody characters, but there still is something that doesn’t quite work. Both she and Gandolfini put on above average performances, but they just don’t jibe well and between the two, that causes Gandolfini’s performance to far overshadow Stewart’s. Gandolfini’s character is so subtle and Stewart’s so over the top, dropping every dirty word imaginable in a single sentence, that she can seem like she’s trying too hard. Their relationship and Stewart’s character don’t feel as natural as they could be, but their situation is interesting and innovative enough that you’re still interested in their circumstances. Shockya.com
It's Ms. Stewart that seems a little out of place, and probabaly out of her depth, with her seasoned costars. Her stacatto delivery is abrupt at times, and not always suited to the dialog, though she does bring an awkward vulnerability to her role that seems to (mostly) fit. -BigPictureBigSound
On the acting front, Stewart is a live wire throughout the near two-hour running time presented here. She comes off like a rabid dog, completely unpredictable; it's easy to see why directors see so much potential in her work. She's great here. See it for Stewart's electric performance, Galdolfini's papa bear strength, or to scout an up-and-coming director in Jake Scott.TheFilm.com
Stewart, by contrast, is all jagged edges and instinct. She's been on her own so long that she's practically feral in her relationship to men. She doesn't know how to respond to Doug's fatherly concern and tenderness at first, except with suspicion. She's been abused so long that she is distrustful of anyone who treats her with kindness. The Huffington Post
Kristen Stewart’s quirks serve her well here, but her ratty appearance and bipolar behavior lend themselves to a drug problem that we never get introduced to. The performance is bold and racy, and Stewart doesn’t seem self conscious at all throughout the film. For a sixteen year-old runaway, Mallory is already close to being irrevocably damaged and Doug and Lois know it and try to take care of her even though the prospect of a healthy nuclear family at this point is highly unlikely. Mallory seems to know it before the Rileys ever do, in fact.Gordonandthewhale.com
Where the "Twilight" movies try to hide Stewart's pimples, here, those natural imperfections (plus a few bruises and suicide-attempt scars painted in for good measure) suit the character just fine. Hiding behind raccoon-eye mascara and electrical-tape pasties, Stewart is the perfect wretch, utterly convincing as a lost girl leveraging her sexuality to compensate for her complete powerlessness. TheVariety.com
Of the three, Stewart probably has the most clichéd role, with her playing the young hooker with a heart of gold. Nevertheless, Stewart does a great job. Sundance has been very good to Stewart this year, with her showing up in two good films, and playing markedly different characters. She's actually a very good young actress, and I hope that her success in TWILIGHT means she'll continue to get quality films like this one made.joblo.com
Stewart is convincingly petulant, antagonistic and suspicious as the foul-mouthed and slovenly young prostitute whom Doug, in a fashion, adopts. Her character’s tentative efforts to grasp the notion that caring and concern are actual possibilities are poignantly rendered by the actress.
Blotchy and bruised, Stewart exudes the troubled demeanor of someone who’s spent the bulk of her life on the wrong side of the tracks and only faintly considers that there’s any way to cross over.web.me.com/tvsoundoff