Does anyone regret getting Invisalign?

1. Wondering if anyone regrets getting this treatment?
   
2. Or was there anything during or after the process, you weren't expecting?
   
3. And how about post-Invisalign care, I heard you need to wear retainers for life? How much will that cost? Any other complications?

My dentist is doing the very hard sell to get me on Invisalign. I understand they are running a business, so I'm being cautious whether this is actually in my best interests long term. Thank you.