I have had this PDA/phone for a year now. I immediately bought a 2GB SD card and screen protector (even though the included flip-up protector does a good job). I loaded it with TomTom GPS software. I bought it because I needed an organizer, and knew if I bought a separate PDA I would end up rarely looking at it. Because this is my cell phone as well, I am always looking at the "home page" where it lists your next appointments. Let's go over a few areas of this product: PDA: Easy synchronizing with Outlook. Many different views for the calendar. Phone: Call quality is good (not as great as my past Nokia phones). I bought the Plantronics Voyager 510 which works very well with the phone. GPS: The GPS receiver is very accurate. The (not included) TomTom Navigator software is also very good--loaded with Points of Interest and accurate maps.
Overall I am very happy with the phone. I have to note that I did have a major problem 4 months ago--no onboard speaker would work, including the handset and speakerphone. HP repaired it and sent it back within 5 days. Battery life on this phone is not very good (needs to be charged every night). At this point, I cannot recommend buying this phone since the new HP HW6915 contains built-in Wifi which the 6515 does not offer. If you can get a really good deal, however, I would buy the 6515, especially if you don't need Wifi.