In my quest to find the perfect lash primer I have tried Clinique, Tarte, Dior, Hard Candy, Lancome, Origins, and now (finally) Shiseido. I say finally because this primer gets so much positive feedback that I had been dying to try it for a really long time.
I also want to mention that lash primer is a staple for me. It is a product that I love generally speaking and I use it every single day. Without it I get smudgy racoon eyes and I love how it enhances any and all mascara. Extra length, extra volume- I love dramatic lashes! Thus the obsessive hunt which led me to Shiseido's Nourishing Mascara Base.
First thing about this lash primer, I was surprised to see that it's more like a clear gel. All the other brands that I mentioned- their lash primers are the white and creamy kind so this was unexpected. The second thing about this primer that surprised me was this- it was insanely hard to wash off. Never encountered that before either. I even did a double-cleanse and my eyelashes still felt stiff with product. So annoying! The traditional creamy primers always wash right off, but this gel stuff just wasn't going anywhere. That alone was enough to turn me off this product unfortunately.
As far as lash enhancement, the added length and volume were honestly pretty great, but the lash separation- very impressive. Smooth and clump-free application too. The effect was nice overall, but not quite as good as what Lancome Cils Booster does for my lashes- it's definitely the best of all the primers I've tried.
I got this as a deluxe sample from Sephora and I'm so glad I didn't pay full price for this- because eventually I would have. Long-time lemming squashed, but it was disappointing.

I LOOOVE IT! Keeps my straight asian eyelashes curled, that's all I ever wanted! I've tried cliniques eyelash primer before this but it wasn't as good as shiseido's.

Love. I have thick lashes that are decently long, but they are SO STUBBORN and hate holding a curl. I hated the Dior mascara base because as soon as I would apply it, my lashes would uncurl, this Shiseido base doesn't do that. It's a rather dry formula, which is probably why it works so well. It's one of the only products that actually holds my curl up and for that, I give it a 5.

First I just want to declare that this product is my HG!

I have stubborn straight lashes that point downward. All mascaras (except for WP ones) drag down the curls. I don't like wearing WP mascaras because they are difficult to remove and many tend to flake.

With this base, I can definitely wear any mascara I like. It will help hold up the curls so easily and nicely. Also my lashes stay soft after mascara application.

I only apply one coat. It dries fairly quickly. It doesn't clump my lashes and doesn't appear white at all (unlike MAC prep+prime lashes). It does lengthen my lashes. But I count on my mascara for length and volume.

tl;dr

For those who have "downcast" stubborn lashes that refuse to stay curled, this base will help eliminate that problem. Very HG-material if you're concerned with curling.

Initially I really preferred the old mascara base but after reading the reviews and following the suggestion to not let it dry before applying a coat of mascara I have had much better results. What I really like is that I can have good results with, apparently, any mascara. I haven't bought a mascara in probably 4 years, but have gotten a lot of freebies - different brands - fgwp etc and this has made them all work. Best of all, I think because I just tried this today, I put it on over my mascara rather than under. Just an experiment because I have eyes that water a lot no matter what and I would always wind up the day with at least one "raccoon eye". I put this on over my mascara at 9:00 this morning, now over 11 hours later with eyes watery as usual, there is not a hint of smearing under either eye and my eyelashes are still fairly curled. I'll try this in public tomorrow and if the results are the same I'm sold forever. The only con I have found with this product is that it doesn't hold my brows in place and the old one did. I'll just have to find something else to do that.

My HG product, cant live without, especially if you have the lashes that tend to point down. Hold the curl all day, I dont have to use it with any other mascara, it work by it own. The price is not too expensive for this amazing products. This is the first product I own from shiseido and diffidently not the last. I repurchase it, again and again and again

Love this. It holds my curl really well with most mascaras and it helps add volume too. I don't think it adds much length though, but I mostly bought it for the curl holding. I also like that it's more of a clear color than white. The packaging says that you can wear it alone for a glossy look but it looks kind of weird.. It is a bit harder to remove than just normal mascara, but still much easier than waterproof mascara. I'll definitely buy this again.

I sincerely feel apologetic for not shouting from the rooftops on this one. Excited from the reviews I purchased two. This is what I did for a week
Tried it with loreal million mascara, no difference, tried one eye with and one without absolutely no difference
Tried it with smoky lash from mufe again no difference between an eye with and an eye without
Maybe a bad batch, or maybe my eyelashes don't need it, I don't know. I wanted big bold lashes. That being said, i owe a big thank u to this stuff...knowing I was going to purchase this made me look at drugstore brands and I found my new mascara love, marcelle twist up mascara - phenomenal. As good as hypnose at a third of the price and I've been raving endlessly about it, def check it out!!!

This is my everything! It's been forever since I've last found it, you don't really run into many Shiseido products in my city. Like I said, I've bought it so long ago, and still have bits of it. I don't really recommend using it without a coat of mascara on, if you have long eyelashes, it appears quite grayish/white-ish on the ends of the lashes. But with my hard to deal with eyelashes, this is the only thing that works! A bit pricy, but lasts long, so definitely worth it!

On its official website, Shiseido states that this product "create[s] unprecedented impact by dramatically intensifying mascara finish." It "enhances the volume, length and curl of every lash". Why is it called a "nourishing" mascara base then? Anyway, I bought this for SGD40 here, in Singapore. It is an expensive product but it does what it claims - it creates volume, increases length and curls lashes. There is a noticeable difference in how my eyelashes look like after I have applied this base and mascara. It is a base so it is a prep step. I have read reviews where people say that you can wear it alone, without any mascara. Unless you want to step out of the house with white residue on your eyelashes, this is not a good idea. When you are using this base, make sure that all your lashes are fully coated with the product. Once you have done so, you can either wait for the base to dry or apply your mascara when it is still wet. Applying mascara when the base has already dried will mean that it will be slightly difficult to apply the mascara. Mascara glides very well when the base is still wet. How your eyelashes look at the end of it all also depends on how good and effective your mascara is. It complements a mascara; it does not substitute it. Overall, this is a good product which I will consider repurchasing.