Textlink is a super useful tool for me even though I don't run "bulk" sms campaigns. I use it daily, and it hasn't let me down at all.
My use case is to send individual text messages to guests in an airbnb context, before, during and after their stay. I create the guest as a contact and use the chat function, so it means I can have a template (outside of Textlink) to copy and paste for sending to the guest.
Next step will be to try out the API so some of these steps can be automated.
Also, I haven't used a separate phone. Not sure why one is needed or suggested. It's worked fine just using my own android phone.