This news is a little old, but the MMO called Seed (their website is already gone, but you can read some info at the out of date Unofficial Seed Wiki) has been shut down after just a few months in operation. Even though the basic concepts for Seed were very creative and unique, there were several factors that led to its unavoidable demise (lack of content and stability being the main two). But the part that really turned me off and resulted in two cancelled accounts (myself and my girlfriend) not even halfway through the 7-day free trial, was the absolutely horrific interface!
Unfortunately, since my playing time was so short and it was nearly 5 months ago, I don’t have a lot of details to list, I just remember it being unwieldy, confusing and awkward. I do remember one specific issue: the in-game help/tutorial. I couldn't figure out how to use it! And this comment is coming from someone who usually dives right into any program and only uses manuals as a reference guide.
When your game needs a help file for the help file, something is horrible wrong. I've done a lot of QA myself over the years, so knowing what it's like behind the scense, I'm generally a lot more forgiving than most MMO gamers, but this game made me seriously question if they had ever had someone who wasn’t a developer for the game look at it prior to release!?
I'm really amazed at how often interface takes a back seat in software development. The interface is the first thing a user sees, and it's their window into your product and their tool for interacting with it. You can have the most awesome code ever written, but if you just slap a half-assed, crappy interface on top of it, then you're showing the world a half-assed, crappy product.