Drawn to these by the inexpensive price tag, and the rave reviews - I grabbed a few of these palettes to try out. The palettes I have are Vintage Romance, Arabian Nights and Ultra Mates V2. (I also had Garden of Eden but gave that away).
I have very mixed feelings about these palettes. As with most palettes, some shades are amazing, whereas some... aren't. In my opinion, the best palette (with the best colour payoff and pigmentation), is the Arabian Nights palette. Filled with beautiful jewel colours, this is super pigmented and fairly easy to blend out.
The other palettes I have by Sleek vary - some shades are amazing whereas some shades aren't that great at all.
In all honesty, I wouldn't purchase any more eyeshadow palettes by Sleek (although their contouring and highlighting kit is amazing). I think for the price they are definitely worth getting, but I have been spoiled by higher end, better performing shadows and so expect everything to perform like those.
If you're looking for inexpensive, yet (mostly) good quality shadows then these are worth getting to try out.
I've seen so many good reviews about the Sleek palettes, but I just couldn't see what was so great about them once I purchased my own. I chose the Oh So Special palette and found the matte shadows were quite powdery and all of them had poor pigmentation. Tried with and without an eyelid primer and made no difference. Such a shame since I love the shade range!