Sad to hear that, I kind of had the opposite experience, and I was staying there during peak holiday season.

Got upgraded into a water-themed suite.

Lost an item in the club lounge. After a couple of days we had given up the hope of finding it, only to have it delivered to us about five minutes before we had to leave.

The service is hit or miss in the club lounge. If they are expecting you, ie. you show up at the beginning of happy hour, service is fast, if not, then you have to seek them out.

I also wouldn't stay here again, but only because I like trying new things, especially in a city with so many options!

If anyone's interested, I have photos of their Water-themed Suite and a mini-review of the property here: http://mintwanderlust.com/sofitel-so-suite-bangkok/