This rubber is (usually) half the price of the next best "cheap, tacky rubber" I can get, with some additional advantages!
For €5 a piece on my latest Ali order (sometimes goes up to €10), I didn't expect much the first time I ordered it. I just added it to an existing order to mess around with.
I have used 729 Super FX several times in the past, and given the low price point of that rubber I will be comparing these two a lot.
Both of these rubbers need breaking in. It takes a couple of sessions to take the stiffness out of the M2 (Mercury 2) especially the topsheet seems to really need to warm up before it will start to give a little bit more.
Booster doesn't help much, on either rubber tbh. Don't waste your time and money boosting them. Mercury 2 comes with a cream coloured sponge that actually reminds me of older tensors like Rakza 7, rather than the high density orange/blue sponges found on Super FX and H3.
The sponge just makes this rubber (eventually) a bit more lively, while the Super FX keeps on playing like a brick, just a softer brick. After a while you could even say there's a little bit of a bounce going on despite the tack. If maintained and covered, the sheet keeps its tack rather well. I have had one for months and it hasn't really changed much at all. I imagine the sponge will eventually give out from under the topsheet but so far it has been in good shape.
The Soft version of this rubber is even easier to pull a ball with, but has a significant power tradeoff. I would not recommend it on FH at all unless you are a complete beginner without power generation experience.
On the BH, it's easy to access its spin capabilities and let the ball sink in a little bit.
The Medium sponge also has a ceiling that's not overly hard to reach, but there is a purpose in having that ceiling, too, because it will basically teach you to not overhit the ball since there's no benefit to be had. I would also opt to use Medium on BH if you have a harder, faster blade. You could probably use the Soft, too, but you'd reach the ceiling so quickly that there's not much of a point to it.
Both sponge hardness versions are just really meant to be stable, spin-oriented rubbers, and that's what they do. Controlling the ball is easy both passively and actively. Serves can be surprisingly heavy on the spin department. Straight up blocking is a bit harder to get right but for a tacky rubber it's actually quite OK.
Looping is easy as you can literally grab and pull the ball. It feels like there's seconds of time to execute your shot. Saving a wide short FH by pulling it over the net is just good fun. In a way, that doesn't really promote good footwork, does it, but still.
Going back to the Super FX comparison, the 729 rubber basically is, and feels like, a classic Chinese rubber, whereas M2 feels like a bit of a modern take on it. It's designed to be thicker, to have the ball sunk into it. 729's version has been updated at some point to offer a blue sponge on the black rubber, but that's all. It also oxidizes like nothing else so it looks like crap within a session.
There's a couple of caveats to M2 though. The quality between sheets can vary quite a bit. We're talking weight, topsheet quality, sponge density, basically every element. For this price point that's completely understandable, but it needs to be said.
Second, and this *can* be important: the old version of M2 is not on the LARC, so it is not allowed to be played in official matches in most countries. The new version, with the spiraling Yinhe logo, is on the approved list, but Ali sellers often don't clearly show which one you're getting.
I am under the impression that old stocks are dwindling, so your chances are getting better all the time. I just bought a stack where the seller didn't show the logo at all and only got new ones. YMMV!
Conclusion: I have said it before in the forums, but if I had to pick one single rubber to use, and pay for, for the rest of my life, M2 would be at least in my top 3. Heck I could use a new sheet every month and be off cheaper than changing most rubbers twice a year.