I've had mostly negative sales experiences here. Incredibly high pressured salespeople bc it's commission based, so they are looking out for their maximum spend, not the customer's best interest. Numerous times had a salesperson try to rush me into the sale of a plant I didn't want and some that were infested (like insects pouring out the bottom in droves or so much that the soil was visibly moving) even after I pointed it out. I've had different sales people give wildly varying care instructions for the same plant (full sun vs. full shade and minimal watering vs. daily watering, etc).
Comparing similar plants, Moon Valley generally has nicer looking plants but are 3-5x more expensive (as in $500 for a Privet vs $150 at other comparable nurseries). The benefit is that they come with free planting and an automatic 3 month guarantee (on larger trees if they plant for you). All that being said, if you're looking for smaller trees and flowers, you're 100% better off going elsewhere but if you're ok spending more to know it's a one-stop shop for planting, it's a good option.
I would still recommend going to other nurseries to get opinions on choosing landscaping first though, so you don't get swindled by Moon Valley's steering you toward a more expensive plant for the sake of driving up their commission.