I have a 319, which is a close relative of this machine. You can modify the bobbin case fairly easily to accommodate a standard 15x1 needle; or if you sew straight-stitch only you can also get away with using a 15x1 - it only causes problems on the stitches that require the needle to swing back and forth. I believe that replacement bobbin cases aren't hard to find, so one could probably even keep the original case in original condition and buy a replacement to modify.
I'm not a huge fan of how cams go onto these machines (kind of a hassle), and I've heard of people with long hair getting caught up in the cam as it turns. These take flat cams, which are a lot harder to find for a reasonable price than the more common 'top hat' cams.
Other than those issues, I like my 319; it sews just fine. I opted not to modify mine and have tracked down some 206x13 needles for it, but it's not my main machine or I probably would get a modified bobbin case for it. Mostly I keep it around for its looks and because it's such a strange machine. (The 319 has these odd levers for switching stitch patterns...very steampunk & funky - love it.)