The smartphone gets a considerable boost in power over previous Treo's with a 144 MHz Texas Instruments OMAP CPU, 32MB of RAM (22MB to 25MB usable) and Palm OS 5.2.1. The Treo line also finally gets memory and peripheral expansion support with a Secure Digital In Out (SDIO) slot. The Treo 600's CSTN display still only has a 160x160 pixel resolution and is smaller than the current screens available with the Treo 270 and 300. It measures 2.7-inches diagonally. However, handspring says the quality of the screen has been improved and is good for both indoor and outdoor viewing. The Treo 600 is slated to use a powerful 1800 mAh rechargeable but non-removable battery for two weeks of standby time and six hours of either talk or online time for the GSM edition of the smartphone and five or more hours for the CDMA Treo 600. The company plans to also offer an optional 1200mAh clip-on battery.

Handspring claims the Treo 600's keyboard design makes dialing the phone and sending messages and email easier than before, even with the significantly reduced size of the product, as it features a domed key shape and improved layout. Each key on Treo 600 has more surface area than those on existing Treo products, and letters and numbers have been enlarged for better readability. In user testing for speed and accuracy of text input, the Treo 600 performed on par with RIM's Blackberry keyboard and significantly faster than Graffiti handwriting recognition found in most Palm OS handhelds, and T-9, the text input method found in most mobile phones.

Unlike earlier Treos, the Treo 600 features a five-way navigation system (up, down, left, right, center) similar to what Palm has been using with its products of late. The navigation system is tightly integrated with the integrated software on the device, making it easy to move within and between applications using one hand. The QWERTY keyboard is also tied closely to the software to make it usable for more than data entry. For example, phone numbers, applications and even specific application functions (such as looking up a specific web page or addressing an email) can be assigned to any of 26 different keys for instant one-touch execution.

Additional features include a new proxyless version of the Handspring Blazer web browser to enable full web browsing and secure access to corporate intranets with better frames and JavaScript support, a built-in VGA (640 x 480 pixel) camera for taking and sending pictures and setting up picture caller ID, and a dual speaker architecture for phone and system audio. A dual-band CDMA radio and a quad-band GSM/GPRS radio will power respective versions of the product.