We use the HubSpot marketing platform and integrate with SalesForce for our sales team, but our marketers needed a simpler approach for lead tracking. And then HubSpot launched their CRM product. It is the perfect solution. The interface is simple and easy to use/understand, while still providing all the essentials for a good CRM. We love that it matches the Marketing platform, and the price point (free!)
The HubSpot CRM is not as robust as larger CRM tools, but is great for the company just getting started with their CRM, or that doesn't have 1 million leads (hats off if you do have that many!)
Honestly, I would recommend trying out this CRM first (it IS free, after all) - and then moving to something more robust if you need to. Be prepared for reps to fall in love with the simplicity and lower amount of "clicks" this provides them.
For the Marketing team, the CRM has allowed us to easily look at the timeline of contacts, as well as find prospects with the prospect tool. And there's no need for us to try and navigate a clunky system for just those simple uses.