The 22 WRM in my opinion is a pretty nice little round and will work pretty good in a variety of situations. Its biggest advantage out of a rifle length barrel over the 22 rim fire is it can do what the rim fire does at more distant ranges. I also like the fact that it can be had in JHP, Polymer Tipped expanding ammo and FMJ. This to me makes it some what more flexible than 22 rim fire ammo. Unfortunately this is not with out a significant cost over rim fire ammo. Despite, its still a small game rifle just about anyway you slice it. Since I am a Bow Hunter, getting close to game is no problem and I would much rather choose to shoot the small deer we have here in Texas with the 22 WRM as opposed to the rim fire. While not optimal and definitely not my first choice in chamberings for this task, it would work well enough for the job at hand with good shot placement.
As for personal defense, its still quiet lacking as a reliable fight stopper against BG's. When you consider all of the flack the .223/5.56 gets in this regard, you can only imagine that a round with only 2/3 of the velocity and 2/3 of the bullet weight, performance would be much more marginal.
I have a Ruger Single Six Convertible that fires the 22 WRM. I also have a bolt action in 22 WRM. So I keep a couple of boxes in about 3-4 different loads around. Its not a bad choice for keeping meat on the table, but beyond that I think it has minimal merit.