I really like it but it lacks:

• Ability to talk to non-gmail users and users of other IM services
• File transfer ability
• Where is the chat logs at? (I know this isn't grammatically correct)
• Group people on friends list together in subgroups other than "alphabet"
• Better way to customize (away) messages (other than "clear all" when you want to get rid of just one)
• Minimize feature for chat windows seems to randomly break