The Dayan LingYun is the third version of the Dayan 3x3 speedcube. Currently they only sell the second version of the LingYun, which just has added torpedoes, which makes it much better. Torpedoes are an added part of an edge piece that hooks under the corners to prevent pops. The Dayan LingYun is a very fast, crunchy, and snappy cube that requires a very light turning style. If you break it in, the crunchiness diminishes but doesn't go away.
The stickers that come on it are badly placed and a little dull, so I recommend replacing them with shades that you prefer. The mechanism is like a combination of the Dayan GuHong and the Dayan LunHui cubes, which makes sense as the GuHong is the second version of the Dayan 3x3, the LingYun is the 3rd version, and the LunHui is the 4th version. Taking a close look at the edges reveals the reason behind the crunchy feel: there are indents on them that are against the direction of turning, causing some friction that makes the turning feel crunchy.
Corner cutting is a little over 45 degrees, and almost line-to-line reverse cutting. This excellent corner cutting is caused by the very shallow scoops on the corners, and the space between the edge and corner that allows the cube to flex a lot while corner cutting. Although the corner cutting is on par with other modern speed-cubes, this corner cutting takes a little more force to accomplish than on many other cubes, so the cube still catches a little during solves. However, this isn't much of a problem.
One thing to note is that the center caps are extremely hard to get off of the center pieces, and they are not quite flush with the edge of the centers. The edges and corners are also extremely hard to get apart, but this is not as big of a problem as the center caps unless you want to do some internal modifications to the pieces.
I would give this cube 3.5 stars out of 5. It is extremely fast, but the feel is not for everyone and there are some small flaws. I would recommend this to faster speed-solvers with a light turning style and who like crunchy, very fast cubes.

As a collectors piece, this is a great puzzle. When it comes to Dayan cubes, this is one that you rarely hear about, and honestly I can see why. This is the V2, which basically only adds torpedoes to prevent popping. Out of the box, this puzzle was pretty bad, which was shocking because the Guhong V1 I unboxed right before this turned rather smoothly. It was very crunchy and locked up a lot on me, and it felt like lube didn't do anything to this puzzle. After breaking it in for a bit, I still can't get a good feel for the tensions and it's still a very loud and crunchy puzzle. It's like a worse version of the Type C IV Witlong (if you're familiar with that puzzle). Keep in mind that this cube is 10+ years old and is NO way going to be something you'd want to bring to a competition. For the collection it's great, but even casually solving it for fun isn't that much of a great experience. Here's a list of pros and cons.

Pros:
Pretty cheap
Smaller size fits in the hand easier
Anti-popping

Cons:
Very loud and crunchy
Locks up a lot
Sticker shades are a bit dull (I don't mind them but I know a lot of people don't like them)

Overall, if you're a collector of old twisty puzzles I recommend you buy one if you can find it. Despite it not being that good, it's still a great puzzle to have.
Pictured below is my Lingyun V2 and Guhong V1 in their boxes.

It used to be my main for a while. It was really good. Popped only because I modded mine, otherwise it wouldn't have popped. Really great for intermediate solvers

It's too fast. Zhanchi's better.

The lingyun has a great feel, corner cuts, but is sub-par on turning.

When I first got this, out of the box it was really stiff and had a dry feeling to it. You could definitely feel the plastic grating against plastic. But with correct tensioning and lubrication IT WAS AMAZING. This cube has so much potential, but has a tendency to overshoot when turning it. I recommend that you are at LEAST sub 30 seconds, otherwise you may not be able to control the speed of this cube. It only has its maximum potential if you can control it properly. Unlike a Zhanchi it has a very fast springy feel, there is not much of the clicky feeling you get in the Zhanchi, it feels more like a Wittwo 2*2, if you own one you know what I am talking about. It feels almost scratchy. Overall turning quality awesome, cornercuts 45 degrees easily, reverse corner cuts a whole cubie, and the stickers that come in with it are your standard Dayan stickers but unlike the Zhanchi the stickers are smaller, I recommend you replace them. I highly recommend this product to anyone who is interested in a VERY fast cube as a main to use at competition or just for fun.

This was my main cube before the SS Aurora has taken that honor. A little smaller than the Zhanchi or the Guhong. Very smooth. No lock-ups and it never popped. A little loose and less firm and less stable than the other Dayans, but I like that. It might be too fast for some speed cubers, which means harder to control. If you think you can handle that you should try it.

I'm surprised there hasn't been a review for this yet. Anyways, this cube definitely lives up to the Dayan standards. It feels a bit more crispy than a Zhanchi, at least mine does. Mine also feels a bit faster than a Zhanchi. Fantastic out of the box and even better once you lube and tension it. Shipping was great, got everything I expected on the expected date.