I've had a 342PD .38+P for several years; use Speer 135 gr GDHP +P "snubby" ammo for social purposes.
GOOD NEWS: It's so light it feels like a kid's plastic squirt gun. Once you get used to it, it's plenty accurate for defensive shooting -- I can get 18-19 (sometimes all 20) rounds into the X ring on a 1/2 size silhouette target at 21 feet. It's very compact and pretty much proof against fouling on anything during draw. I'm keeping mine. . . .
BAD NEWS: When a +P round comes to life in the li'l sweetie, you can really tell something happened. 50 rounds will usually give me blisters and a sore, shaking hand; 20 proficiency rounds with reasonable results does it for me. When I first got it, I was having accuracy issues and sent it back to Mother Smith. Talking to 'em on the phone, they chuckled politely, told me nothing was wrong with the gun, and to quit flinching. They were right. The Speer "snubby" ammo mentioned above has good terminal performance, somewhat reduced perceived recoil and muzzle flash, and a lot of PDs are using it. It's sometimes hard to find.
IMHO, .357 mag in a snubby revolver is a waste of time -- most of the powder burns out in front of the gun. What you get is an impressive blast, blinding flash, and sore hand. I guess S&W makes little snubbies in that caliber because lots of folks buy 'em.