It is only automatic search (tree-matches) that is not free. You can still use the search field in the top left corner, with a few exceptions in the advanced section.
What features you get is however not locked, and as far as I know none-Pro users will get more of current Pro features and new Pro features will be added.
The most important update in near future is better revision handling, which includes reverting changes.
Requiring a card-number to get advanced features like cutting connections and uploading gedcom's (currently disabled) is important for me because it forces people to identify them self. There has been a big problem with fake accounts and abandoned GEDCOM uploads.
Becoming a Pro member does NOT help you finding your ancestors, simply because Geni is not building the tree, - the users are, by collaboration and sharing sources.
You could take a long-shot by for example start a public discussion posting a link to a profile that is a dead end for you and ask if anyone can help you.
The term used to describe the business model is Freemium.
Freemium is a business model that works by offering a basic product or service free of charge (such as software, web services or other) while charging a premium for advanced features, functionality, or related products and services. The word "freemium" is a portmanteau combining the two aspects of the business model: "free" and "premium". The business model has gained popularity with Web 2.0 and open source companies.
If somebody wants to be pedantic, then the better complaint will be with the word "professional".
A professional is somebody who gets paid for what they do, as in "professional basketball player", "professional dominatrix", etc. But on Geni a "professional" is a hobbyist who actually paid to do their hobby, i.e. a complete opposite of a "professional".
Geni have for e along time ago started to name it Premium Subscriptions
Ah, the mysteries of English slang & subscription branding!
I recently watched (again) "West Side Story" (1961). The authors "invented" their own teen slang "jibber jabber" as they were aware how quickly it could become dated ....:):)
Lois is correct that a "basic" membership is a "neutral state.". It is not a "less than" meaning in terms of using Geni.
So a "pro" membership is a "more than" value.
Perhaps change the badge to +> for better internationalization.