Hi,
I've been using both Zoho and ThinkFree. ThinkFree is definitely the deeper and feature-rich from them - basically it's a full office package.
I can send an invitation to the premium beta if you'd like.
Zoho is cool and useful for occasional tasks - i'm using it mainly for project management and less for office tools. But it is a stable suit and Zoho are constantly adding features and listen to feedback.