I love this bag, nice, simple, easy.  It was smaller than I initially though.  I bring a pair of shoes, water bottle, gym towel (like a small hand towel), phone, wallet, keys, and a change of clothes (gym shorts, shirt).  It is just about at capacity with that.  I can't fit my lifting belt in there if I have all of the rest I mentioned.  And if I am wearing a jacket I usually have to start scrunching it in there.  Luckily I have a punching bag in my house I use so I don't have to use a gym for that, but if I did it would be a problem putting all of that in there, rummaging around for it, etc.

In the end a larger bag would allow me to carry more but I only go the gym for lifting, jump rope and other things I do at home, and this is just at the perfect size for me.  I might get a larger back for the winter months to be able to store extra clothing and such.

I also use this bag as just my normal sort of everyday bag as well.  On days I don't go to the gym I still use this to bring a water bottle, my phone, wallet, keys, maybe some cereals bars or similar type of food to bring to my cubicle, paperwork I might need to bring, flash drives, etc.  Just a general bag.  I wear basketball shorts as my job allows me to so, why not be as comfortable as possible, so I use this bag to store what would otherwise be in my pockets.