If you are referring to the most recently updated design, it is considered the 2015 model year and was available for purchase in March of 2014. This explains the jump in sales beginning in that time period. I have to disagree with you, I think the design is outstanding. I am not armed with sales figures, but I just did a 16 state road trip and saw them everywhere. Based upon my own evidence, they are popular and selling fast.
What I don't like is the wannabe Mercedes "luxury interior", lack of NOT leather interior options, lack of interior and exterior colors and the continued lack of a tailgate instead of the hatchback (for soccer moms). I'd also like to see a diesel available on at least a 2500. However, I'm grateful they reconfigured the back seats to lay flat again so you can use it like a truck. Over all I would consider buying one, but I would go with the GMC Yukon rather than the suburban because I like the front end styling better.