UPDATE: I've changed the price rating to 3 since it might be expensive for a bottle of oil but it lasts forever. I've barely made a dent in mine. And lowered packaging to 2 since for some reason, it's constantly hard to open: seems like the lid and dropper form some kind of vacuum and keep the top too tight. And in general, the product isn't a great as it seemed in the beginning. It's still good, particularly for fine hair, but not as smoothing as before.
ORIGINAL REVIEW: In many review sites, this is a love/hate product but for my hair - fine, dyed, very dull and very very dry - it works beautifully to restore shine and texture without adding weight or greasiness. Simply put: it makes my hair look normal and nice.
You need to ignore the instructions however and figure out the best amount and timing for yourself. Instructions claim to use 1-2 drops warmed up in your hands on damp or dry hair. For me (shoulder length hair), it's 4-6 drops warmed up - all together or in two steps - only on dry hair. I also work into the driest areas and ends, then run over the top of the hair. While I do use other serums e.g. Moroccanoil and Frieda, even applied sparingly they often look like I've got oil on my hair. This doesn't. Plus, while I normally need to wash daily, this has doubled the time I can go without shampoos.
Just for reference, my normal hair products are B&B, Davines and Kerastase. I tried Ojon products several years back and they were either too heavy or did nothing so I never considered the brand again. I got this as a sample and have been using it constantly. Just placed an order for the full-size. Only reason I gave it 4 stars rather than 5 is that it's especially expensive for its small size.