I have a MiFit, another cheap FitBit wannabe. It’s very accurate - I have no idea how it knows whether I’m walking or just fidgeting, but it does. It syncs to my iPhone and the advantage is that you can see a record of your steps over the past week, month, etc. It can also give detailed information about your exercise (route, average speed, incline etc), but I don’t bother much with that, nor with the heart rate readings. I do like the sleep monitoring function, as I’m trying (and usually failing) to get more quality sleep, and it’s helpful to have a record of the time you nod off, how much deep sleep you manage, etc. It only needs charging once a month, and that just takes an hour or so.
If you simply want to count steps, though, I’d recommend a cheap-as-chips Daffodil pedometer in your pocket.