I always stick with the Janomes. Whether it's a computerized or a mechanical model, they always are so dependable and powerful. You never get tired of them. By the way, you didn't specify the exact model for the Jamome Jem series.
Either way, I find the 3/4 size of this series as well as the "Hello Kitty" 11706 3/4 size sewing machine I actually own since 2011-now discontinued-the best of both worlds. Compact does not mean under powered. Simple small menu of stitches does not mean impracticable or limiting or even just for beginners. Do keep that part in mind no matter what model you choose if you go the Jamone way.