yes it is

but work good

Is it expensive, like the rest of these inhaler?

One of the things you'll learn is that what works for someone else may not work for you at all. Trelegy is a combination of a LAMA, LABA and ICS (those are all all classes of medication). If one of the three doesn't work for you, the whole thing may not work. The only way you'll know whether it works or not is to try it. And the only way you'll know whether something will work better is to try it. So whether anyone else like it or not really isn't the issue: the issue is does it work for YOU?

I have been using Trelegy for a few years and have done well with it. I also used Breo and Anoro before and have done much better on Trelegy. I do always rinse my mouth out thoroughly after using an inhaler....sometimes I will just brush my teeth as well. I have not had any problems with mouth sores or thrush.