Overpriced for simple items, missing features.
Site does not even have a box to upload a picture into on selection nor in checkout. Was trying to buy a mug with custom text + picture, but found far better alternative (Estonian site called Funbox) with similar idea and half cheaper! Lelks is missing multiple boxes to fill out specific things and instead relies on just one text box for you to say what you want on the mug along with limited options in terms of type of colour etc (you'd have the blue mug handle version, but no blue version for the mug's inside part). One box does not do the full job and to add an image file you'd probably need to contact the seller, which doesn't make any sense given the more expensive price you're paying for.
Neutral 3-star review due to not having bought anything, instead just providing information about the seller.
Otherwise, it seems fine. Nothing deceptive or scammy, just that you will probably have a better time elsewhere due to a lack of liberty to just add in preferences + image file yourself without contacting the seller on top of getting better prices for a simple mug or wine glass.