Quirks? Well,.. there are a couple.

I'm fairly convinced that either product labeling for calorie count is off, or this thing doesn't give me an accurate calorie count. To maintain I need the program to register about a 500 calorie deficit.
Entering the calorie count for restraunt meals is almost impossible - you can get close using nutrition information websites and the like,. but you never really know what was in it.
You WILL find out that a meal at round table Pizza can EASILY top 4,000 Calories
They have their servers down for maintenance more often than you might expect. It seems like once a week I have to wait till the next day.
If your a computer guy you will find the site a little slow and clunky - it could be better done, but it does provide good and helpful tools.

Helpful tip - it charges through the USB port, so get into the habit of reading it before your shower then leaving it plugged in during the shower and it should never actually go dead. When I was in Moab Utah I didn't have much availability to power (We were wheeling and camping) and it was pretty dead toward the 4th day, but it did last for 4 days without connection to a computer. A quick hour charge boosted it for 3 more days.

In the end,.. if given the option I would buy it again, but it may not be as slick and refined as someone might expect.
Whiskey