Let's start with the limitations before moving on to the strengths...
There's espresso and there's espresso. A good espresso grinder not only needs to grind very fine, it must also allow the user a great deal of control at very fine sizes in order to get the best taste from a given blend on a given day.
If you want to make good espresso, you're not going to do it with this grinder. You can make a Smart grind fine enough for espresso, but it will never give you enough control for good espresso.Shims or no shims... Not enough control. To make things perfectly clear, there are NO good espresso grinders anywhere near the Smart's price.
On the other hand, and it's a big other hand because there are so many wonderful ways to make coffee besides espersso, other brew methods don't require the same degree of fine adjustment. That is for everything other than espresso, the right grind size will be far more about the method itself; and very few brewers need day to day adjustment. Get it right once, and you've got it right forever. The Smart does a great job for those.
More often than not, we drink espresso and use a speciality espresso grinder for that. But, every few days as whim dictates, we choose French press or vacuum siphon. FP wants a fairly coarse grind, while smack-dab-in-the-middle medium is best for the siphon. That's when we use the Smart, and that's where the Smart shines.
Grind size is extremely consistent at both sizes. That is to say, with the Smart set at its best setting for FP, all of the grinds are coarse; while at the medium setting, all of the grinds are medium. That there are so few fines makes for (relatively) clear French press -- which is a rare and good thing.
There's more adjustability than the readout might have you believe, which allows the user to dial in a fairly precise grind. There are four different finer/coarser (palpable and audible) click stops between each visible setting. Just as good, the settings are very repeatable. We are able to return to the same settings time after time no matter how often we switch sizes for different settings. For example "3 plus a couple of clicks" is just right for FP, while a bare "7 on the nose" works for vac.
The volume setting -- i.e., how many cups -- is more than good enough for our types of brewing. For instance, "6 cups, plus two extra bumps stronger" is always right four our 8 cup French press pots; and "7 on the nose" is right for the siphon. (Odd that the "couple of clicks" and "on the nose" hold for each pot, but there you go.)
The plastic cup is not as static prone as some collectors, but do expect some static clumping.
The machine is easy to maintain, clean, and so far has been extremely reliable.
The worst you can say about this grinder is that it's not built as well as the top wide-range adjustable grinders like a Ditting, a bulk Bunn, or a Mahlkonig.
But apples to apples? The Smart's got much better build quality and grind consistency than almost anything else in the price range, including the very good looking but lousy functioning Kitchen-Aid. Its only real competition is the Baratza Preciso, and the only significant difference between those two is looks.