For the most part, they are good enough. It doesn't work well in all situations though. It's a useful weapon to have in the armoury as it can save a lot of time on some jobs and make them easier. Other times, it can be a mess. First cleans may be far more time consuming as you might need to go over them a few times with very frequent pad changes. Thereafter, most jobs will be easier if cleaned frequently enough. There are plenty of exceptions though as some types of plasticated partition glass stays smeary.
Test it and find out which jobs it works on. Even if it's only half of them it may still be worth it.