I've been using a Fitbit a little less than a year and I like it. I regularly check my steps, sleep data, and exercise logs. I don't adhere to any sort of daily goal or metric outside of the 10,000 steps, but it's nice to monitor my overall fitness routine on a daily basis as an additional motivator. I don't use it for the calorie counter, because weight management right now is not a concern for me.
I can't figure out the cardio load. I thought nothing of it, but all of a sudden after three straight days in the gym (which is not uncommon for me), it alerts me to take a recovery day for the next two days, like I'm no the verge of a cardiac event. I'm not even sure what the metric is, and am too lazy to find out.
I've read some reviews comparing the Apple Watch to the Fitbit. Seems like you want the Apple Watch for music and other aspects of basically having your iPhone on your wrist, but as a fitness tool I'm not sure it's clearly better. And you have to charge an Apple Watch almost daily, where I can go about 5 days between Fitbit charges.