Questions for SodaStream users

My wife is thinking about purchasing a soda stream or similar variant for Amazon prime day. I would like to hear the pros and cons of owning one. Are there any costs of ownership that were not apparent? I don't want to buy another kitchen appliance only to stop using it because we couldn't keep up with the maintenance or other required issues. We do buy regularly la croix like drinks from Costco so if there is truly a cost savings that would be great. Thanks for everyone's time and opinion.

Edit: Wow thanks everyone for the responses and insight. I will have to sit down later and work through the posts. I know I will have more questions.