No it is not, it is more of an anticonvulsant than anything. Clonazepam has ok muscle relaxant properties, great anti-anxiety properties, and poor sedative properties.
It's not the best in any category. Lorazepam is a superior for panic attacks and about equal for general anxiety, lorazepam is also a super anticonvulsant, and a stronger sedative aswell.
Alprazolam (Xanax) is better than clonazepam only for panic attacks, they are about equal for general anxiety (if not, clonazepam might be better in the long run). As sedatives, they are equal and clonazepam is a superior anticonvulsant and it is a superior muscle relaxant.
Diazepam is also all around superior to clonazepam in just about everything. It's a stronger sedative, stronger muscle relaxant, superior for panic attacks, and I'd say probably equal for general anxiety. As for anticonsulant properties, diazepam and clonazepam are about equal in that area. Diazepam is better for acute seizures and clonazepam is better for long term use as an anticonvulsant.