Roshi is strong but not over the top STRONG like you would want.

He is vulnerable to blitz team and the only team I see make use of him well currently is EM because he gets a good amount of shield from EM. He is supposed to get buffed after 3.0 but Germany ROshi after 3.0 didn't get buffed as of yet or I have heard at least.

Totally up to you man, personally I have fun with him but not one of my main choice as a ninja yet cause I am limited to EM to make him work.

Also I know there are alot mains you can do with him but unless you are EM he gets blitz out round 1 too fast since about 99% of the time Roshi is in slot 1.

Just giving my 2 cent on Roshi.