What I find interesting is that I had no problems with the controls at all, yet others are grumbling about them. Who is right and who is wrong? Could it simply be that certain folk just aren't able to get used to the sensitivity of MotionPlus?
Motion controls are always going to be on a person to person basis of effectiveness. If you play a fighting game, a hadoken is always the same input. Down, downforward, forward is a static, unchanging move that is being inputted incorrectly if you can't get the move to work.
With motion controls, everything needs to be more broad. A thrust attack is done by jabbing the wiimote forward. It can't be TOO sensitive so it doesn't come out when you're just holding the controller and naturally move forward a bit, but it can't be too hard so that nobody can get it out unless they almost stab the TV screen. But making it broad opens up a can of worms when there's tons of overlap. Speaking of overlap, go back to the hadoken example. A shoryuken is forward, down, downforward. These overlap the same inputs, but are still different enough so that you can always get what you want. New players, however, have trouble with this. They may be moving forward, want to quickly do a fireball, and get the shoryuken instead. Eventually this becomes a science that you master, and you never input the wrong move, even under pressure.
Now, the thrust again. If you thrust at an angle, you're going to get a diagonal slash. When I do the thrust too fast, nothing comes out for some reason, or the thrust comes out when I pull back. Given the nature of the move, I WANT to do it fast, but the game doesn't accept that for whatever reason. I need to slow it down and be sure I'm going straight. Still, in pressure situations, it's hard to not do it fast, and if my hand is tilted I get the wrong move. It's harder to train yourself with these controls over a normal gamepad. I think a lot of people naturally hold the wiimote at a slight left angle, which actually means horizontal slashes MAY become diagonal. I say may because it is all in the way the game interprets the motion, it's no longer a static thing. The game needs to quickly accept a motion to not appear laggy, but it has to be accurate enough to not keep giving the wrong move.
On top of this, people's experiences are influenced by their setup. It doesn't matter what time of day it is when I'm playing street fighter, my fireball input is never going to change. But when your setup is right by a window that is letting in light, you can confuse what the game is looking at, and give you the wrong things. I play at night, and the swimming is the one input I really don't like in this game. Where I was normally sitting, there's a lamp nearby me. The swimming was just acting wonky as hell, always tilting in a direction I wasn't going, making it unenjoyable. I had to move and sit on my coffee table(which is not a comfortable way to play and hurts my back if I'm there for an extended time), but swimming now worked fine. I was doing the same exact motions, so I wasn't doing anything "wrong", it just was getting messed up by something. The lamp? Actually, no. I turned it off, moved back where I was, did the same inputs and swimming was still acting messed up. I don't know why.
Even FURTHER, there can be faulty equipment. Whether it's the sensor bar, the wii itself, or the controller. With a gamepad, it's obvious when it's broken or atleast getting there. You can feel the sticks getting lose, buttons stay pushed down, etc. With a wiimote the game is still going to be reading some sort of input, and it won't be nearly as obvious on a case to case basis.
So nobody is "right or wrong" here. I'd like to think people having issues with the motions aren't lying, and it can be very frustrating when you are performing a thrust fine, the game just won't recognize it, you make a post about it and just get "you must suck". There's a lot of factors involved here, and while the game surely performs fine for many, there's also a fraction where the controls don't work nearly as effectively for a ton of potential reasons.