Yes, you are legally allowed to print for personal use. I've bought plenty of e-patterns & they all print just fine. Only thing is that in some cases you have to either take the printout to a copier to blow it up to proper size (they'll tell you how to do that) or it prints full size & you have to tape it together.
Of course, I've also bought paper patterns that had to be blown up on copier, so it's really no different.