Snus is quite common in my country, Sweden. Many users are former smokers who "quit" by using snus instead as their source of nicotine. Users I know have said that they feel that it is highly addictive.

Studies of snus users have indicated increased risks of cancer in the mouth, throat and gastrointestinal system but have not been conclusive as to how. There's also a newer type of snus not made from tobacco, with pure nicotine as a separate ingredient, but it has been studied much less.

Nicotine is still widely considered harmful for the cardiovascular system though. I've had two surgeries this past year and been told to not even chew nicotine gum for a week before because of how nicotine in my system could lead to complications.