I first received a non-magnetic 7x7 for some reason but I'm glad that they sent me the magnetic one very quickly after the call.
The Yuxin Little Magic 7x7 is SLOWW out of the box but very stable. The inner layers are really sluggish and hard to move. Loosening it helps a bit butI don't recommend that since it pops and locks up a lot. I took the screw out along with the spring... and the spring was very strong. So I cut off at least 2 full 360 coils with pliers and then the cube was lightning fast. The cube still retained a great stability however the turning was sooo unbearably papery so I put in vaseline. This made the cube have the best feel I've ever felt on a twisty puzzle.
Magnets are a great strength. Outers are pretty weak but the inners are quite strong (2nd and 3rd layer have the same magnet strength). This makes the big center in 3x3 stage stay together while the outers move very fast but the magnets are just strong enough to keep the layers aligned.
The cube has never popped or locked up at this tension but still allowing corner cutting to be about one piece and half for reverse.
I can turn very comfortably on this cube and can go as fast as I want with it. During 3x3, the outers catch a bit when going to fast but it's easily fixed and never results with a lock up or a pop.
Beginners: Get the YuFu. It's over 10 dollars cheaper, faster out of the box and requires a lot less setup.
If you want to get serious at 7x7 and have a budget but knows how to set up…