If you've been using FatWatch 1.4 or earlier, here are some key changes in 2.0.
If you have a scale that reports your body fat ratio, you can being entering this data into FatWatch. When computing Trends, FatWatch will automatically use body fat numbers if they are available; total weight otherwise.
If you have been recording your body fat in the Note field, you can transfer these numbers by exporting the data from your device and then importing it back in. If the number is the first item in the Note, you won't have to modify the file. Otherwise, you might need to manipulate it (e.g., with a spreadsheet application) before re-importing it.
If you would like help with this process, don't hesitate to contact me. I may develop something to automate the process if I find that many people have similar setups.
One of my design goals for 2.0 was for FatWatch to do a better job of telling you how to achieve your weight goal. I changed the Goal feature because it wasn't accomplishing that very well.
In 1.x, the Goal line was based on a start date in the past. As time went by, it would become less useful, especially if you strayed from your plan at all. For example, a display of "-300 cal/day" on the Goal view was basically saying, "If you go back in time to your start date and then run a deficit of -300 cal/day, you will make your goal on time." Possibly interesting, but probably useless.
In 2.0, the Goal line is dynamically computed from your current weight. You no longer see it overlaid on your history (but it is projected into the future), but now it can tell you what you need to do to get to your goal, as you are right now.
If you are following the exercise program described in The Hacker's Diet, you can now track your current rung within FatWatch. Switch to the More tab, tap Marks, then tap the yellow (last) mark. Tap the Use for Exercise Ladder button to enable.
Once enabled, you can select your rung by tapping the yellow mark icon from the weight entry screen.
The Trends screen has been redesigned. Specifically, it will now show you how your weight over a given time period is trending relative to your goal. If you are moving faster or slower than your plan, FatWatch can show you equivalent amounts of food or durations of activities so you can get an idea of what you need to do to get back on track.