I guess that would depend on what metric you wanted for 'successful'. He certainly was successful in perpetuating the Principate setup by Augustus. From a governance standpoint he maintained the state's coffers and borders but these successes are somewhat negated by his later effective abdication from power and surrendering it to Sejanus.

So I would give him a decidedly 'mixed' stamp. He definitely left the empire in a good position but he lacked the temperament to be the princeps and this led to his self-imposed exile to Capri. Compared to the most politically astute Augustus he was a bit of a disaster but if we pull back enough to compare him against other Julio-Claudians like Caligula or Nero, he looks a lot better.