I guess what gets me most disappointed is that I really felt like the game was going to be 'bigger' than it turned out to be.
When I saw the concept art during the GDC video, and yes I know it was never confirmed stuff for the game and just simply concept art, my mind went crazy thinking of the areas to explore.
When you take those images and combine it with the dialogue coming from Bungie in their vidocs, it was hard not to get really excited for something big.
I had visions of landing in a huge open world, where you could go anywhere and explore. You could find random structures off in the distance. On your way over to a big, distant structure, you would encounter random batches of enemies. Maybe you would be blocked by a powerful enemy, and just before he kills you, another random more powerful player snipes him dead from off in the distance. This allows you to continue to the structure while the other guardian goes off on his way, and you think to yourself 'wow, what a legend that guy is' I started thinking this 'become legend' rhetoric was legit.
Yes, these kind of moments can happen in the game now, but on a much smaller scale. The public events are really nothing challenging, nor are they interesting. It's cool to see random guys get all worked up and come together, but the activity itself is never really satisfying.
But what really got me down was that these destinations funnel you in limited directions. When you land in a destination, you land in the same spot every time. You know exactly how many enemies will be to your right and to your left. It's the same setup every time.
Plus, and I don't mean this in a literal sense, but your options in explore mode are basically go left or right. You can't go up because you'll hit a wall. You can't go down because you'll fall off a cliff and die. If you happen to work your way around these obstacles, you'll be met with a 'turn back' notification. I can't help but think of the e3 video where the guy said 'See all this? All of this....is playable space' and there were plenty of moments were I just wanted to speed off to areas off in the distance only to hit an invisible barrier. I know you can't build worlds that go on forever, but man there are plenty of times were I just think to myself 'ugh, thats so lame' while exploring. There's also very few interesting areas hidden away. All you really get are a few caves tucked away that spawn enemies that also contain the occasional loot chest. And the structure and depth of these caves are exactly the same every time; it's total cut and paste. Beyond that, there really aren't many spots you'll get excited about discovering.
While I understand you don't just move left or right in explore mode, the idea is there are only so many places you can go. Plus, the game is basically telling you where to go anyway. Head left to pick up these missions, head right to pick up these other missions. You never really have the choice of going anywhere you want or the freedom to discover something for yourself.
My hope was that you could find tons of cool things to explore. Maybe you'll find a sweet chest in the basement of a distant structure, one that will reward a sweet gun hardly anyone else has. They'll ask you, where the heck did you find that? And your answer won't be that simple. What you discover in the actual game, though, is quite easily explained, since there rarely is a secret path to take.
It sounded so big in the beginning. There was going to be this huge, vibrant world where tons of crazy, random, and exciting things could happen. So much to see and discover. So many things that keep you coming back again and again. Instead, we already know the whole experience. You know exactly what Old Russia is. And unfortunately, the only time you'll get to see just a sliver more of it is when those 'DLC doors' open up at a later date.
I could go on and talk about the story (what story) and pvp and all that, but it's all been discussed already.