Having not played the game yet and only watching about 10 hours worth of gameplay footage… well maybe 20…
Pro’s: I’d say that this is shaping up to be a very popular game. The free-form building, fps playstyle and open world is great. The crafting has been excellently implemented. Sure, it needs to be finished up, but for an alpha, it’s amazingly simple and easy to use… and it freaking works.
Con’s: It’s too early to judge negatively, so much could change. My initial worry is the blandness of the scenery. What’s there is awesome, I must admit.
There’s no variety and it feels very… well, bla. This is surely going to change, however.
There are no weather effects which has become somewhat standard in many popular games today or at the least varied environments. Who’s to say that won’t change as well.
Concerns: I hope they can strike a balance between size and player volume. You don’t want it to be too crowded, but at the same time you want player interaction to be necessary.
I’m quite impressed for an Alpha release, and I’ve been around since the ultima online days, and tested a LOT of games over the years.