Enjoyable show, was worried that it wouldn't do the manga justice but it does a pretty good job.
Also, Alpha Tomasowa's review is incorrect; he clearly didn't understand the ending at all.
SPOILERS
It turns out a meteor crash in Tokyo caused numbers of people to fall into a coma - these people's consciousnesses entered Borderland. If they died in Borderland, they wouldn't wake up from the coma and they would die. The people that cleared Borderland would wake up with their memories of Borderland gone, which is what happened at the end. It wasn't just one person's imagination, like Alpha was saying. At least understand the ending before writing a misguided review about it.