Sleek is a makeup brand available in UK drugstore. However, their products are also available for international purchases on their website. I'm a big fan of these shadows - they are smooth and pigmented, and last all day on my primed eyelids. Bonus: Pixiwoo uses these palettes all the time in their makeup tutorials.
For fun, I compared some of these shadows to what I already had in my collection to see if there were any dupes. Surprisingly, nothing really matched!
Now there are minor disadvantages to the shadows. For one, they do have a bit of fall-out if you're not careful when applying them. They do not fall out during the day, but application can be tricky with the softest of shadows (#5 is a bit problematic) as they can have a tendency to crumble. For me, a bit of fall-out is nothing a swipe of foundation brush can't fix. Also, most of my Sleek palettes, including this one, have duds. The duds here are #3 and #7. They're not horrible, but they're not as pigmented as the other shades, and they apply a bit patchy and dry. I don't love MAC's matte shadows, but they are much better than the two Sleek mattes in this palettes.
Favorites in this palette include #1, #5, #7, #8, and #9. Based on these shadows, I think the palette is worth it. Especially at such a low price point. Some of these shadows aren't colors I would consider wearing on a day-to-day basis, but are really great for a dark smoky eye on a night out.
Hope this review was somewhat helpful in helping you decide whether it's worth it!