1)Performance can be reduced. becuse the viewstate is stored in the page itself, storing large values can cause the page to slowdown.It can carry only up to 10 KB of data very easily without causing any degraded perfomance.
2) As view state is stored in a hidden field on the page although it stores data in a hashed base64 encoded format, it can be tampered.
1) No server resources are required
2) simple Implementation
3) Automatic retention of page & view state