Ok so it is now fair for me to review the Valkyrie add-on to GOF2. I've clocked about 26 hours into the game and I'm now piloting one of the top Vossk ships around. I've also purchased my own space station and I'm starting to store tons of materials, weapons and add-ons. I've got about six blueprints and I used the Khador drive to travel to distant galaxies. I also unlocked the liberator missile, which is a guided missile system. Honestly these missiles are amazing and the guided view is amazing.
There are a few issues I have with the game such as once you've used the Khador drive and you have to unlock it again to travel to distant galaxies you must collect 50 tons of Void crystals which can only be found in the Void system but unfortunately if you beat the main campaign you cannot access the Void system again. On the official blog for GOF2 they claim you can purchase 50 tons of Void crystals in the Wolf-Reiser system. For me this is not the case. I've been flying around to almost every space-station looking for Void Crystals. Apart from that the exploration of the game is pretty fun, you can unlock new galaxies that have advanced technology. Once every few hours the game will crash but I think it's expected due to the size of the game. So Valkyrie is priced at $4.99 and is well worth the money, Fishlabs has put in the time and effort into this add-on and hopefully in the next year we see another add-on or GOF3.