Not brilliant. I bought a set a few years ago.
You can sharpen the chisel reasonably well but the augers leave a lot to be desired.
It all depends on how much morticing you need to do.
I think Custard posted something on sharpening them?
I do wonder whether all the cheaper-end ones are made in the same factory, can't be that many factories making them anymore. I do remember reading somewhere that there was just the Harima factory and one other in China that still made them but that might be wrong.
If in doubt buy the cheapest. Seems to work. I've only ever had one major dud - a Faithful No 10 plane which was beyond use.
On the other hand if you spend 10 times as much and ask yourself what you are getting for the money the answer is usually not a lot. Better finish and nicer looking seem to be the main things.