Pros: Somewhat effective, almost throwaway priced. OK for a non-demanding user.
Cons: Noise cancelling is very weak and audio is pretty awful, but still...
Compared to nothing (in the way of noise cancelling) these are better than that.
Damning with faint praise? Yeah, I guess so, but really what can you expect for the price.
Sony makes a product that generally is worth buying, if it meets your criteria.
If in this case the criteria is cheap, light weight and easily portable you are in luck.
If it is for noticeable noise reduction, again you are in luck.
If you have any pretensions of being an audiophile, and getting high quality audio, well, that's not going to happen.
These do offer some noise reduction, and being on ear, as opposed to over ear they really can't isolate much.
I would say, bump your budget up to closer to, but still under $100, and you can find much more effective noise reduction, as well as better audio.
These are barely acceptable, and then only for non-discerning listeners. One feature I appreciate is the use of a replaceable AAA battery. And the long life these give using that one battery.