NEW YORK ( TheStreet) -- After 13 years of using all previous BlackBerry ( BBRY) models every day, and now one month with the all-new Q10, I'm going back to the previous BlackBerry. The new Q10 simply failed me in a couple of critical areas where compromise is not an option.In brief, to spare you the suspense, the most critical failing in my experience with the BlackBerry Q10 was that it was unable to synchronize my Gmail address book with accuracy and/or reasonable speed. There are a couple of other big problems, too, but I'll get to those later. Before you start penning your hate mail, let me say this: My situation may vary from yours, for multiple reasons. I'm speaking from the perspective of someone who uses only Gmail accounts for contacts sync. My address book is also large, not too far away from Gmail's 25,000 contacts limit. If you are on a corporate server, or your contacts synchronize over USB, or you're with Yahoo! ( YHOO) email or Microsoft's ( MSFT) Outlook.com -- or perhaps even if you have only very few contacts in your Gmail account -- who knows, you may not experience what I experienced, and therefore be just fine. I wouldn't know. This review is from the perspective of a regular individual who only uses only Gmail for contacts sync. What do I mean by the Q10 being unable to synchronize with the Gmail address book? The problem manifested in three stages: Stage 1: The initial address book sync took at least in the ballpark of 24 hours. That said, one doesn't know exactly, because the Q10 doesn't provide a count of how many contacts you have. You sample some number of contacts, and see if they made it to the device. In comparison to a relatively new high-end Android phone, a category of which I have tested several recently, the Androids appear to have almost no latency in this initial availability of the Gmail address book. I haven't measured exactly, perhaps because it appears synched instantly after you input your Google ( GOOG) credentials into the Android. Stage 2: Once you believe the initial sync is done, it's time to make some additions and changes on each side -- Q10 and Gmail. Long story short, some changes appear on the other end, eventually. Others don't.