Ham will be a bit drier and stronger flavored when thawed, but is still fine. If it's a smoky ham, it'll be smokier; if a salty one, it will be saltier. But I freeze it all the time, and lord knows my mom froze everything! As you thaw you'll get a little puddle of water; freezing draws out the natural water in just about anything you freeze. Pour it off (or dab with a paper towel) if you don't want the liquid (if you're making soup, well, toss it in).