You no longer need a smart card reader, for example, so you can use it from virtually any computer. One potential problem with tokens is ease of use. Some tokens are time dependant, so if you do not punch your PIN in fast enough your login credential may have expired by the time you use it. This is an aspect of authentication systems that is typically ignored or given very little thought. While a lot of attention is paid to the strength of encryption algorithms and tamper resistant properties of the items, people seldom bother to find out what happens when the system is compromised in some way.
Tokens are relatively easy to deal with once stolen and compromised.
The shared secret is simply removed from the authentication servers and a new token with a new secret is issued to the user. The next time the attacker tries to use the stolen card it simply doesn't work. Smartcards, on the other hand pose some significant issues once compromised. Because most SSL based software packages have the root keys built in, the certificate on the stolen card will still work. Unfortunately, very few vendors use this field and not all software packages support it.