I don't feel like the acting is weak. Allow me to delve into details.
Spock's nasal voice instead of the deep register we've come to expect from Nimoy struck me as "off". I immediately expected that I would come to find it annoying. However, the actor faithfully captures the Vulcan's calm, direct demeanor. I chalked the nasally, nerdish voice of Spock's actor up to an "interesting actor flaw".
Then there's McCoy. I could easily imagine Kelly sitting down with a nice young girl or two in the woods, playing acoustic guitar. He was kind of one of those rustic hippy sort of personalities. Grating and sensible, but romantic and passionate. Yeah, well, this new guy is a tad overweight and smacks a tad of "gay". However, I think he perfectly captures the McCoy character. We can chalk up what's lacking to Kelly's interpretation. This new guy delivers perfect deadpan, which is pretty important for McCoy's sarcastic and wise wit.
Kirk was a good Kirk. As others noticed, he obviously studied the hell out of the part.
Scotty's, well, original Scotty's son apparently. He obviously enjoys the part and puts a lot of emotion into it. He almost looks like he's going to break into tears out of love for his precious Enterprise and the illogical and unnecessary danger she's being put in. He's the consummate engineer.
And there's Sulu. That guy delivers with so much arm-swinging gumption it's hilarious, but he keeps it so muted! He never crosses the line into cheese-land! And did you see him almost cracking up on the bridge? It's obvious that Sulu's actor will be able to deliver with just as much subdued grinning as the original.
Uhura obviously loves her part, as well. She really shined during her delivery in the opening of the "rec room 6" scene. I think the way she held herself on her forward foot was a slight bit ungraceful, but wow, what shoes to fill. The original actress for Uhura was a real smooth woman. I think this girl does great, most importantly she gets into the part. Maybe when her hair gets longer, she'll put it into a more 70's do.
Everybody else was pretty much carbon copy of the original.
Somebody mentioned the sets being CGId to look plastic-textured. I beg to differ. I think some of those sets were built with a lot of plastic. It's not like they don't have access to it -- obviously they built the space suits. The hallway leading to the recreation room, check out those joist panels coming down from the ceiling. That hallway is definitely built.
The lighting was really picturesque, too. No moment was wasted with washed-out effects.
Personally, having seen the recent big-budget reboots with all the camera lens flare covering everything up, and having seen this other fan-made thing "Phase II" that seems to prefer dark and blurry shots, I think there's apparently a sort of guilt complex hazard in making a remake of such a famous show. I'm sure the directors feel like they can't live up to it and so the lens flares and blurs and darkness are supposed to offer the audience a chance to suspend disbelief for fleeting moments.
That approach doesn't work for me. This approach that "Continues" is using, where everything is well-lit and filmed in classical style, it spot-on. It allows them to go a step further and showcase that actual thing called The Writing.