If you are a small/medium business and use Salesforce as your CRM, there's really no reason to consider anything else. That's where Pardot is by far the strongest. If you are looking at more of an enterprise solution, then at this time you probably still want to look harder at Eloqua or Marketo. But a year from now, I'm guessing Pardot will even have a stronger case for those situations. It's a great time to be using Pardot.