From what I saw, the Yiynova tablets are great except for that pen slight jitter
The MSP19U tablets don't have any pen jitter, except at the very edges (~5-7mm) of the screen and in the corners. I ordered mine from yiynova.eu (Netherlands) and have only positive things to report so far. It was delivered very quickly, the software installation took less than 5 minutes and then it just worked (tested in Photoshop, ArtRage and Sketchbook). There is only very minimial lag and it seems to depend more on the software that you use and your CPU rather than on anything else (I had some minor but noticable lag in ArtRage while none in Sketchbook and only very little in Photoshop - it may depend on the document size and the brush, though; I was mostly sketching with a small brush).
I miss the ability to map pen buttons to keyboard actions and need to press much harder with the pen than on my Intuos 3 to achieve the same line quality, but none of that is a deal breaker.
Nevertheless, despite being a fine device, I will probably try to return it for a full refund. I would like to stress that the reason for it isn't any fault with the tablet, but the fact that I simply cannot deal with the cursor parallax. Unfortunately, it's the nature of the beast and Cintiqs suffer from the same limitation. However, if you can deal with the parallax and are on the verge of whether you should get the MSP19U or not, my advice would be: go for it!