If you are looking for true CRM functionality in a system with leads, opportunities, contact management and a funnel, Intervals doesn’t do that. However, Intervals can be used as a sales tool to keep track of leads and bids. A sales project can be used to keep all of your template documents stored within Intervals that are needed for your sales process (maintenance contracts, sample bids, etc.).
Then a task can be used per lead to keep track of conversations, iterations on the estimate, etc. With email integration you can Bcc the task whenever you email your perspective customer to keep the task up to date with the conversation. If you win the contract you can close out the task and create a project to execute the work.