There's a lot of different variants - carbines, rifles, old Czarist guns, ones used by Finland, ones made in America under contract in WW1... Without knowing which kind, it's impossible to really comment on the price of 150 dollars. There are also recent production "sporters" featuring American made synthetic stocks.
In general they are simple and robust rifles. It's been written that a monkey could operate one. Since Stalin did once try to bring about human/ape hybrids for cannon fodder, there might be truth in that. The action won't be exactly smooth. Most will benefit from a slip on recoil pad. Getting the 17" spike bayonet is a nice accessory (on a full length rifle) since if you run out of ammo, you have an effective pike. (Also displays nicely.)
The full size rifle versions tend to be a bit heavy, long and ungainly by modern standards. They also lack the safety features built into other (near) contemporary designs such as Mausers. (Life was cheap in Russia. The Czar, and later the Red Army, had plenty of conscripts.)
The carbines are handier but tend to kick and produce some impressive fireballs.
Sporting ammunition is readily available. Brass cased reloadable ammo can also be had. If you reload, get your particular rifle checked since dimensions seem to vary a bit in the neighborhood of .308-.311 but that's to be expected given the huge numbers, long service life and many nations involved in manufacture.
Commercial scope mounts are also on the market. A fair number of people make inexpensive but useful scout rifles out of the carbines.
I have a nice 91/30 with all accessories in the closet. Once I put the bayonet on, it stayed locked on. Maybe I shouldn't have helped it on by whacking it with that board. Eh. Probably be useful hunting wild boar since the boar spear is now built in.
As cheap rifles go, I actually prefer the Carcanos, though ammunition is more expensive and enbloc clips are starting to dry up.
Mosins did see use as sniper weapons over the years, and the people of Finland made some impressive match grade and sniper weapons out of them over the years. However in general accuracy is going to vary greatly from one example to another for the simple reason of the size of the pool that yours might be drawn from and wartime variances in standards.
Whether one is right for you depends on what you want to use it for, your expectations, etc. Given the low cost it is difficult to go too far wrong though.
