I have one.
We just had to operate on mine tonight--there was a bit of thread stuck on the back side of the tension disks. However, dh got it out. (The thing I don't like is that I can't get easily to the tension disks to get that stuck thread out. I don't know if we invalidate the warranty if we take the cover off, etc. to get to it.)
It has happened one other time in the two years I've used it--intensely, I'd have to say. My DH observed, "I don't think that they meant the machine to work as if it were in a factory!" as I sometimes put 5-8 hours a day in (if I can--other days 1-2).
I've had to replace the foot pedal (went out in Feb.--a year and a half of hard, hard use) and just recently I had to replace the plate because the automatic plate converter (for making it wide for zigzag and smaller for straight stitch stitch) broke. Neither of those two things were covered under the Janome 3 year warranty, I was told. ?? (I was a bit bummed by that.)
But, it normally FMQs so well--til tonight--then I noticed I had no tension --thread was in the disks. As I mentioned before, we operated, so to speak and got it out.
So, as soon as I pull out all the loose bobbin threads in the quilt I was quilting, I will use it again. It really is a nice machine. I can't fault a machine for having a few problems when I've used mine as much as I have.
It is my first "higher end" machine as my other ones (since marriage) were $200-300 models. Both were Pfaffs purchased here in Poland. Before coming to Poland, 18 years ago, I had Singers, probably purchased at yard sales. None of them were "fun" to sew on. I think that the Horizon has totally warped me and raised my standard probably for the rest of my life, which is okay (I'm 50). It is a heavy duty machine and you just feel confident in it--it is sturdy and dependable.
I've used some of the embroidery stitches and they were nice. I haven't used all of the other functions. I did use the applique stitch (as recommended here) for putting on appliques a few days ago. I don't use the knee lifter, but I love the stop/start button and used it for a while before replacing the foot pedal. The needle threader and thread cutter are wonderful. I like all the harp space.
Lowering the feed dogs is so easy, it seems like it should be harder. The even feed is super easy as well....I really like it for putting on binding or straight line quilting (have started doing that as well.) Mine is not picky about thread.
That's my opinion...I'm kind of a new quilter, but not a new seamstress.