Depends very much on the brand and size. Some are fine, some are awful.
Example 1: Triangle Talon in 225/40/18 - really, really awful. Unbelievable noise (sounds like a wheel bearing gone), and zero grip when the road is anything other than bone dry. These came on a set of wheels I bought, and I decided to try them out as they had 7mm tread left. After 60 miles, they are coming off, the car is effectively undriveable.
Example 2: Sunnfull in 225/40/18 - couldn't fault them. Came with the car, I wore them from 5 mm to the limit, and not a twitch, wet or dry.
Example 3: Accelera in 235/40/19 - can't fault them as summer tyres, they get a bit interesting below 7C. As I run winter tyres, this doesn't bother me.
No idea on LandSails. Rag them through a few puddles and see how they are. Naughty of the garage to fit them without asking.