I love that Zoho CRM has an API allowing remote retrieval and update of CRM info. I also like the fact that one can add custom fields.
Room for Improvement:
Can't think of something I dislike about Zoho - CRM.
I use Zoho - CRM as my customer management tool. I am dealing with a few hundred customers. I have easy access to account info, contact info, recent notes and activities, and problem tickets.
Towards the end of last season's project, I wrote a script to calculate revenue from each customer. I did not have to manually update the CRM, since Zoho provide a cool API able to retrieve and update CRM data. Recommended!