After reading numerous 5-star reviews, this $14.99 cube seemed like a steal at $5.99 --however, this thing's got some issues.
Firstly, this 3x3 is as crunchy as a pepper mill, just very, very noisy. Then, the cubes are extremely difficult to square up and so it catches with any slight misalignment, which seem unavoidable. (I tried both tightening and loosening the factory tension and saw no improvement to these issues.) Also, the edges are very sharp and some of the cubes have seams that refuse to stay closed.
Maybe these issues are indicative of the Maru Mini CX3S's 4-year-old design, or maybe I got a defect, but this is one of my least favorite 3x3s. If I had paid $14.99 for this cube I would be returning it. At $5.99 it will be okay in a lineup for multi-cube endurance drills.
I gave it 3 stars only because: (1) its current price is a third of its list price. (2) when it does turn properly, it seems relatively fast. (3) Its corner cutting is adequate, though not outstanding.
I will say it is nicer to solve than a dollar store cube or other brands, but only marginally so.
For 2 or 3 bucks less, the QiYi Warrior W blows this cube out of the water performance-wise.

The cube feels and handles great. The compact size makes it easier to carry around and allows for smaller movements when turning.
However after a few weeks, many stickers partially didn't stick anymore and started to come off. Additionally one of the corner pieces started to come apart.
I'm rating 4/5 because it's definitely worth the price asked.

My first run through of this cube was smooth. It is already tensioned and turns absolutely amazing. The corner cutting is great, it could do a little just over 45. I would highly recommend this CX3s. It is the perfect sized cube and fits in your hands perfectly.

My first run through of this cube was smooth. It is already tensioned and turns absolutely amazing. The corner cutting is great, it could do a little just over 45°. I would highly recommend this CX3s. It is the perfect sized cube and fits in your hands perfectly.

Great cube. The corner cutting is over 45 and reverse is a whole cubie. It is very fast, the fastest cube i own. It only pops when reverse corner cutting, but only sometimes. It lowered my times from 18-20 seconds to 15-17, I was using a shuangren before I got this. The cube has a bumpy and catchy feeling, but I don't mind it. Great cube overall.

I seriously can't lie when I say that this cube dropped my times by about 5 seconds. I was shocked by how much better this cube worked for me compared to something like a ZhanChi or an AoLong V2. The cube feels crispy and crunchy but feels smoother once it's broken in. Corner cutting is past 45 degrees with some effort and reverse is effortlessly half a piece.

I seriously can't recommend this cube enough. It's fast, crispy, controllable, and it dropped my times after using it for only a day.

I solve about 19 seconds and this cube is my main. when i got it i expected it be be better than what it was but after about 500 solves and figuring out which spring set and tensions i like, it is amazing! I hate the soft springs by the way...
Cons: extremely loud, has the worse center caps ive ever had(every time you do an H perm with some speed at least one falls out).
Pros: very fast, corner cutting is descent, light, sticker shades are perfect for me.
All in all, it is my main but i havent broken my pb with it. Also, it is kind of weird, but doesnt bother me, but if you like flick it, the whole cube vibrates in your hand, but it doesnt do that when your solving so no worries

Aside from being loud and a little bit sharp (the corners and edges) this cube is incredible. With the soft springs in you can tighten it to the point where the cube will never pop and can still cut 45 and reverse cut 2/3. The speed is on par with the AoLong and Weilong and has a very unique feel. The original CX3 was always underrated and this cube is even better than that.

This cube is great I love it its just as good as my weilong but this one is crunchy and a bit snappy compared to a buttery smooth feel of the weilong, but its really worth the money, this is a great cube I highly recommend it to people who are sub-20 to sub-10 because it really is more of an advance cube like the weilong or the fangshi or even the zanchi, buy for anyone else, it might be a bit uncontrollable because it is pretty fast out of the box, no lube so far and almost beat my average of 5 of 14.90 by .1x

This cube is somehow a weird cube. I expected somewhat more of it. Pros: I love the color, transparent blue and phantom bright, love the weight, pretty light.
Cons: Loud, clicky, bumpy, catchy, corner cutting is a little less than 45, reverse is little less than have a cubby- medium tensions. BUT...it pops really easy while reverse corner cutting. This is not the best cube ín the world, far from it. Great for beginners and for collectors but i would´t recommend seriously speedcubing with it, it will just pop on you or the catchiness will mess up your perms.
At 15 bucks its an expensive cube compared to the quality you`re getting.
I´ll stick to my along mini as a main cube.