I just watched the Eng dubbed version released very recently. Now, given I already the manga so I wasn't surprised with anything, I still loved watching this. The voice for Minato is the main reason I wanted to see it, I always wondered what voice would fit him. At first the voices don't seem to fit, but shortly after it works just fine.
For those who give a shit about Naruto but don't know Kakashi Gaiden: Long story short, it reveals how Kakashi got his Sharingan.
For those who give a shit and know about it: You should watch this and tell me what you think
For those who don't give a shit (Raiden): Why did you click this? Oh flame me thats right.