I've had two major problems with Candid:
1) The results I experienced with Candid did not match the models they showed me to entice me to purchase their aligners. My teeth did not move in the way the models indicated they would, despite following the Candid guidelines to a tee. Reaching out to their support team was a horrific experience. You'll get orthodontic "advice" from low-level support people who I'd imagine struggle to put on their pants in the morning. The quality of support I received before and after I became a customer was like night and day. Everything was smooth until they got my money, then it seemed like they couldn't care less about me. I didn't get what I paid for and Candid, despite their shiny marketing to the contrary, WILL NOT HELP YOU.
2) Shipping was a nightmare. After receiving my 3D models, but before paying for the aligners, I had 2 Candid associates confirm that they'd be able to ship my retainer to my new home overseas. Naturally, this turned out to be untrue. My retainer was apparently shipped to whoever is living at my old address (Candid sent the retainer blindly without asking what address to ship to). Following up with their support team had them inform me that they would only ship within the US (despite what 2 of their employees had previously told me). So now I have no retainer.
I feel like this company stole $2,000 from me. Don't make the same mistake as me.