I've 3 of this style from different brands. All very practical and good if you don't want to take much with you. I can fit my small purse, keys, phone, lippy and one pair of glasses (which is the only pain).
If you can get one where you can interchange the strap that is great (only one of mine does that - the other two are fixed straps).
I love the colour of the Ellie Beaumont one.