we installed Mr Cool mini splits last year - they are amazing for cooling. Silent and super efficient. Our house was cool and dry all summer and electric bills less than the window units we had before. They can heat in a pinch, but we found the electric usage was really high and was more expensive than our gas heat. i do use it sometimes to warm up our sons room because that radiator is undersized. I suggest watching a lot of youtube installs and reading about btus :) i designed the system and my husband installed it. It was complicated due to the layout of our home. I'd say its not for an absolute beginner handy person - but doable if you are patient and careful. Btw - we bought way too many pre charged lines that we'd be happy to sell for a loss if your interested. Overall it cost about 6500 for 5 indoor units, 2 condensers, the electrician and the outdoor line covers.
Our lowest estimate from contractors was 17k and highest 30k to install central air. Our home is 1800 square ft.

you need to remember that these units are all good units BUT if you have a bad installation or bad sizing with no information then they wont work right. just make sure its PROPERLY installed and that the unit you buy is the correct for the use you need. i understand the allure of those precharged lines but i have hear a lot of bad things. my unit was properly vacuumed and charged to EXACT amount of refrigerant per manufacturer. this is VERY important with these types of heat pumps

Ops system is good down to -22f, will lose BTU's but will still put out heat, the standard MR. Cool wall mount units with the "quick" connect lines are not low ambient units and are only good to about -5F and lose almost 50% of their BTU output at that temp, so size your system accordingly..