My view of CY (Europe based):

CY varies a lot from different continents - I stayed at CYs in the US, Europe and Hong Kong.

US CYs:
I stayed at: Tuscon Williams Centre AZ, Hesperia CA, Merced CA, Palm Springs CA.

I learned the lessons from FT here and try to avoid CYs, but not all the time I can avoid them unfortunately.

The 4 CYs I stayed at, Hesperia CY is by far the best (brand new when I was there). The others were hopeless - paper thin walls - I can hear what the neighbours were watching (fortunately they are not making porn or moaning), the towels were grey and thin and it doesn't absorb water anymore. The bed were bad - it makes noise when you turn or move.

I like a microfridge in my room when I'm in the US and CY lacks that.

Both PS and Merced had kids, football team and dogs while we stayed there. Put it this way - I will continue avoiding CY in the US as a default (unless they are the cheapest).

FFI is a luxury motel/inn IMO, and I like them a lot - especially for the newer ones (In fact I only picked the newest ones). The breakfast varies a lot - some offer the absolute minimum but other offers more than that, one even had manager reception which is a free dinner! As a tourist, FFI is a great choice.

European CYs
I travel on my own dime so I can't afford FS Marriotts in Europe, so CY is a great choice. Their rooms are nice, especially their double beds are not 2 beds move into one.

The price level for CYs in Hamburg and Bremen (the 2 places that I go frequently) is around EUR 20 higher than their competitors. They still get my business because they are better than those hotels. A non-smoking room is a non-smoking room (some hotels claim that non-smoking room is a room without an ashtray).

I like their CYs have modern design and a spacious and comfortable rooms - personally I think those CYs I stayed in beat those FS Marriotts in the US in terms of space and decoration and the toilets.

CYs in Hong Kong

Hong Kong is the only place that I have stayed at CYs (the other FSs are really out of my range). The rooms are ok, nothing special. They have lounges - which I rarely use because of the food outside being a thousand times better. Again they are 20% more expensive than their competitors and I'm used to be happy to pay for it due to Megabonus, now I have to rethink about it.