JD Ultimate is good and makes a noticeable difference for me, plus has nice features such as WIFI on location, etc.
The one major problem for me is that none of my auto email sync attempts have resulted with a regular schedule of checking my emails. Enabling push, adjusting schedules on both email and JD, setting the email program as an exception that is allowed access to data in JD, none of them resulted in having emails checked ever 30 minutes. Sometimes it was 12 hours before I'd get a message on it's own without me manually checking. Deal breaker for me, as it's the point in having a smart phone.