The 50th 357 is the same gun as the New Vaquero in 357, except with adjustable sights. Along with the 44Spl, these are the only adjustable-sight mid-frames built so far. Both are excellent guns.
In 357, these mid-frames aren't as strong as the large-frame 357s but it's cylinder is still beefier than a GP100, so it's certainly not "weak". It's a perfect size gun for dealing with the outer edge of the 357's envelope, it's beefy enough to take a nearly unlimited diet of monster loads and heavy enough to control 'em one-handed. It's basically the perfect 357 single action.
My daily carry piece is a New Vaquero in 357 with modded sights. When I bought it in 2005, the 50th 357 Blackhawk was more expensive and harder to get, so I settled on the NewVaq and eventually upgraded the sights past Blackhawk specs. No regrets, but it would have been easier starting out with the 50th 357.
Now that the 50th 357 has gone dirt cheap? THAT is the best SA 357 available short of a Freedom Arms.