I have had my Horizon for about 16 months, and despite a few glitches (two motherboard replacements!), I love it.
Topstitch needles are essential IMHO, especially with the King Tut thread. It is one of my favorite threads and for a while there I thought I would never get it to work with this machine!
Try loosening the top tension, I find I have to do it trial and error with every project. I always make practice sandwiches using the same fabric/batting.
Really, it will get better!