I have had the Calmini rack on my Xterra for a while and here are my thoughts...
Pros:
Stronger than factory rack
Lower profile than having to put a rack onto your factory rack (Yakima, Kargomaster, Con-Ferr)
Yakima stuff will work on it
Has light tabs
Matches lines of the vehicle
It is not blue
Cons:
At the time I got mine it did not have a replacement basket (I believe that Calmini is getting that taken care of)
Lights on roof can cause some light flooding into the windshield (due to them being so far forward)
Does not have spiffy wind dam like OE rack (when they release the basket then you will get that)
It is not blue
Overall I have been pleased with the rack. I had to replace my factory rack due to it falling apart. There are three cross bars that support whatever type of floor you want to use and the space that is created is larger than any of the most popular baskets.