W = poor service? Not in my experiences.
I don't think the W concept is poor service, but of course poor service can and does happen at any hotel from time to time regardless of the brand.
I stayed at the W SF a year ago as a gold and experienced amazing service. I booked a "pay for 2 days get 3 days" long weekend in the cheapest category room available and was a gold at the time. I was upgraded to a high floor with a fantastic view of the Bay bridge (and this really meets the terms of a gold upgrade). I was given this room at 10:00 AM when I checked in, fantastic to not have to wait until the afternoon and again, above and beyond on the hotel's end. On my last day I wanted to go online and print my boarding pass but the business centre was closed. I asked at the desk if there was a chance I could get in for 10 minutes and they said no problem. They sent someone up with me who cheerfully let me in and they did not ask for any charge for this service. Needless to say I'm a fan of the W SF.
One more example of W service would be my last stay at the W Court in NYC. I was upgraded to a suite. Upon showering the first morning the drain was a little slow. Not a huge deal or a "nightmare", but a problem I simply mentioned to the front desk on my wait out that morning. When I returned that day the problem had been fixed and there was a very nice fruit and wine basket left for me on the desk with an apology note for the inconvenience. To me this is above and beyond and one of the many reasons I love returning to W hotel's.
There are many more examples (like the time the W Times Sq store was out of an item I wanted to purchase so the hotel manager told me to take the item in my room instead free of charge) so I don't think "W = poor service" is a fair generalization. I'm sure there has been poor service given at W's (and Westin's and Sheraton's and Hyatt's and Marriot's...) but I don't think it's fair to categorize a brand that way. I'm more curious as to how hotel management respond to poor service when alerted at the time of stay than to how a letter is responded to later.