Neutral:
* Verbose
* Prolix
* Loquacious
* Talkative
* Garrulous
* Voluble
* Long-winded
* Rambling
* Wordy
Negative:
* Chatterbox
* Windbag
* Motormouth
* Blabbermouth
* Rambler
* Logorrhea (medical term for excessive talking)
* Circumlocutory (using unnecessarily long or roundabout language)
Positive (in some contexts):
* Eloquent (if their wordiness is skillful and persuasive)
* Articulate (if they are clear and concise)
* Expressive (if they are able to convey their thoughts and feelings clearly)
The best word to use depends on the specific situation and the intended meaning.