I bought this about two weeks ago and decided that I'll add my two cents to this discussion.
A foreword: My ideal foundation match is Siberia in the Firming Foundation, Siberia in Sheer Glow being too yellow. On a daily basis, however, I'm using Graftobian's Ingenue topped off with Snow Loose Powder (which it needs because it's slightly too dark and won't stay put otherwise).
In regards to everybody saying that Finland is too dark for < NC/NW15s; try putting on less. The coverage is higher than that of a regular tinted moisturiser from what I can see (it comes close to Sheer Glow IMO), so you really only need that pea-sized amount. If you have any blemishes or scars to cover, try a good concealer. The new NARS concealers in stick packaging seem to be quite good; I use Laura Mercier's Secret Camouflage. If you have melasma or red cheeks, try dotting on some more TM in those places and blending it.
Otherwise, personally for me, this is HG material. I'm quite serious about sun protection because I use retinoids, so I use La Roche Posay's Anthelios XL SPF30 or 50 under my foundation. Using the NARS TM, however, eliminates that step. Furthermore, topping it off with any loose powder is optional too, if you have normal to dry skin like me. I'll still use powder on my T-Zone just to take the shine off and to add a matte contrast to emphasize the dewiness of my cheeks. I even slept in it (I know... a big no-no!), and it still looked darn well the morning after.
I do have some flakiness around my nose, and it doesn't seem to emphasize that. Sheer Glow is much harder to work with if you have flaky or dry skin. It's too early to say if the silicones in this have made me break out. It's that time of the month and I usually get one or two spots.
Overall, I'm very pleased to have bought this! Applying my base takes just one step now instead of three!