The bottles are really great, this is my second set and they have never failed me - it doesn't matter what you do, they don't leak. I wish they made one size larger than the ones on this set - in longer trips I have to take two large ones.
Why not give it 5-stars? First because the bag that comes in the set is just lousy - unlike the bottle themselves, the quality is very poor: the first one disintegrated after one month and the second one had the zipper unglued after just one week. Second, as the bottles are made of silicone, it is very difficult to mark them to identify the contents (I do not use them only for shampoo and conditioner but also to lens cleaners, anti fog, etc.
Despite of the critics, I would still buy more of these!