I'd say not really. An yet, I like to use them a lot.
So you can likely get a room upgrade but the size of the upgrade isn't very noticeable because they tend to be smaller to begin with.
Their breakfasts tend to be awesome, at least in Spain.
I've always been treated very nicely even before I was a platinum--I was gold last time I stayed there.
I like their clean modernist lines. The hotels seem both bright and dark. That suits me well, but may not be for everybody.
Beds are always great and comfy.
I was an AC fan before they became Marriott. I know there's some people that don't really like the ACs, but they serve my needs well.
Thanks for providing such a helpful answer, homoviator! To piggy-back off of that, Platinum members will still get the normal benefits that are associated with similar brands such as a Courtyard. One difference is that The AC does not have a lounge.
Hope that helps!
I concur with homoviator, I stay at the Paris Porte Maillot frequently in fact 5 nights next week. They always treat me great and most always with an upgrade. Beds are great, very clean room, great gym, great location in Paris (for me anyway). True there is no complimentary breakfast and it's 250 point for Plats (welcome gift), awesome front desk staff. If other AC's are like this one, then I'm a believer...