Would you advise someone to buy it, or move to another caliber
That depends on what you want it for. My knee-jerk reaction would be to say, "Go to another caliber". You probably don't want to use a large single-action revolver for home defense, and it's too large for concealed carry. Most experts say that a .30 Carbine (especially from a handgun) is too small to hunt deer-sized game, and if you're looking for a varmint handgun, you can probably find one in an easier-to-find, cheaper to shoot caliber. However, if you have another firearm chambered for .30 Carbine, go for it.
With that said, I have one and I like it - a lot. It is fun to shoot and it is quite accurate - at least
I think it is - I can usually get sub-3", 6-shot groups out of it at about 40 yds with the factory sights from a rest. It shoots pretty flat too.
I bought mine used for just under $300 because I have an M1 Carbine and wanted a handgun in the same caliber. I don't know how hard it hits since I've never hunted with it but "they" say it has ballistics similar to (but slightly less powerful than) a .357 Magnum.
One thing I noticed: Factory ammo is designed for a carbine-length barrel. When fired from the Blackhawk, the muzzle flash is extreme. It's also very loud. When I take this gun to the range, I usually get at least one, "What the heck is that?" comment.
I've seen some published load data for .30 Carbine that are formulated for a handgun. I plan to start reloading in this winter; one of my projects is to try to find a load that works well in the Blackhawk. I've had good results with all brands of ammo except American Eagle. It was very hard to eject the spent American Eagle brass - I had to press a wooden dowel onto the extractor and tap the end with a screwdriver handle. For what it's worth, I consistently get the best groups with Magtech ammo.