It's cool that they have two SIM slots and an SD slot. I wish more phones had that. But the removable battery doesn't seem to be particularly large.

Its not, and its a smartphone from 2015 with a SD800 with 2 GB RAM. There's a lot of pros and cons about it, but at least you can repair the components yourself. Just the other day I installed a new camera module, all on my own. I also replaced the battery. For a mere 20 EUR. (The camera module was front + back for 75 EUR.)