I usually carry a S&W 642 with me most days. It's so lightweight that I often forget I even have it on me. There are no safeties to deal with, and I’ve never had it malfunction on me. The J-frame size really does disappear when it’s in my ankle holster or pocket, which is great for carrying it every day.
The downside is the capacity. You only get 5rds, and thats it. Reloading takes a bit longer compared to switching out a mag. But honestly, for a defensive gun, I think it’s more than enough since you’re probably only going to fire 2 or 3rds at most in a real situation. For me, the simplicity and ease of concealment totally make it worth it.