The architecture doesn't hide much of the table structure. There are tabs for the major entries like contacts, leads, and accounts, and each tab has similar buttons for creating new entries or searching the old ones. There are a few wizards in some of the areas that need more hand-holding. One for generating e-mail campaigns, for instance, checks a number of configuration options to make sure the messages go out correctly. I wouldn't be surprised if the tool is most heavily used to send marketing messages.
The software is written in PHP and tuned to MySQL, although it can be adapted to work with other databases, including Oracle. The community edition comes with all of the basic features for filling out the tables with names of people and the meetings between them. The dashboard keeps a constant tally of the new leads and what happens to them. The system has always had a sophisticated plug-in structure, and there's one site, the SugarExchange, devoted to cataloging these open source and professional plug-ins.
One random estimate cited in Wikipedia says that the community edition includes 85 percent of the features of the professional versions, a fact that's probably based upon the number of tables in the database, not on the coolness of the features. The professional and enterprise editions come with some of the fancier enhancements, like more sophisticated reports, a customer portal, and mobile access. Most of the sophisticated plug-ins come at a price.
It's easy to get the impression that the community edition is being eclipsed by the professional version, especially because most of the marketing copy on the front page of the SugarCRM site is aimed at getting people to try and then buy one of the professional versions. And if you're already running the community edition, SugarCRM is ready to make it simple for you to upgrade to the proprietary ones. But there are substantial resources devoted to the community edition, including a number of forums and SugarForge, the repository for the main project and many plug-ins.
I think SugarCRM is doing a good job of supporting both the open source community and the substantially larger set of businesses that just need something with a few more guarantees. The forums are actively monitored by paid, official helping hands, but most of the discussions are focused on the trials and tribulations of installing the community edition in different environments. There's an active community of non-employees that maintains the simpler versions for businesses, and many are digging into the code to move around buttons, change URLs, share a log-in with another package like Moodle, or even modify the database tables.
The vitality of this world seems to bleed over into the professional editions. SugarCRM seems to have more newer features, like integration with third-party databases and social networks, than either Openbravo or Compiere, if only because there are so many projects in various stages of completion. The experimentation from the open source community fertilizes all of this creativity.
The module builder for SugarCRM lets you create new data tables and then build the panels for editing and displaying the tables with drag-and-drop tools in your browser.
At the same time, the company is clearly looking to help whenever it can for a fee. It just introduced Sugar Express, a product that matches hosting with the community edition. It's $499 for a year's subscription for up to 5 users and $799 for a year's subscription for up to 10 users. The prices rise if you go for the features in the professional version. The first tier is $30 per seat per month, and the full "enterprise" tier is $50 per seat per month.