A small deduction I do because of the connector between two rails, this is not 100% fit (slight shoulder edge), too, has a little too much play, so that during the assembly possibly a rail at a slight angle is different from the first. Here is a searching and careful look of distress that does not look it wrong later.
The lamps can be a little hard to move, but this is mainly to do with the orientation at the start.
Basically, I would buy the product for this price again.