Among the comments in other reviews about the positioning of the buttons or 90 ° -sized cut: In an article, which you can turn on both the base (camera pan) and up (ball) to 360 °, you can philosophize long, where the front and is back. If I ever considers that, in the brand name is at the front (is Nikon, Canon and all other so ;-)), then I would have the button for the camera pan back, the recess for 90 ° forwards and the lock button on the left (as you can you hold the camera with beautiful right). And if you need time for vertical shooting the 90 ° swing left, then you have to turn the whole thing around 90 ° stop. While this is not in the manual, but should be manageable anyway ... Can you ever use the way so if you want! ;-)
The slight resistance when moving the ball does not bother me, when working with the monopod, I feel that even positive: when the lock is not completely tightens, the camera remains pretty stable, keeping them anyway in hand. And if you take needs to correct the position, gives the ball freely with slight pressure and slips nicely into a new position.
In summary, after 25 years of experience with various Tripod ball heads and Neigern, mostly from Cullmann, I can only say: a strong buy recommendation for Sirui!
Supplement 7.3.13:
After me sometimes the supplied Removable TY-70-2 was too short (due to weight distribution, especially with the 70-300 zoom without a tripod clamp), I bought the Benro PU release plate PU100 series. From Sirui there is not (yet?) No longer removable disk. The plate is indeed narrower than the TY-70-2 (such as the smaller Sirui) but longer by 30 mm. During clamping there are no problems, the panel blends well with his head. More details in the review of the Benro ...
Otherwise I can (certainly a day ...) only confirmed the good impression after 5 weeks of intensive use. "Real" long-term exposures (minutes), macros from snowflakes at minus degrees in the woods, product photos in the home studio ... everything was great.
Bottom line: If I could, I would give it a 6 ******!