Everybody else is doing it, so here are impressions:
Right off the bat, I'll say it's good. I know many people feel differently, but the game gives me serious Halo vibes. The familiar combat loop is there, and it again focuses on the triangle of guns, grenades and melee. Strikes change this up a bit by including bosses. I feel they're a tad bullet spongey but still pretty fun to fight nonetheless. The class abilities are there but they're not as defined with strengths and weaknesses as I had hoped. This is first and foremost an FPS; don't expect MMO-style fights with each player serving a unique role. Still, firefights are interesting. The AI is responsive and fun to combat. Environments are purposefully designed and allow proper positioning before engaging.
Speaking of environments, this is where my biggest issue with Destiny stands. While fighting on them is fun, they feel restrictive in terms of exploration. I've often been met with "turn back now" zones or just straight up invisible walls/kill zones. There are a handful of nicely hidden secrets but on the whole, I don't feel as free when roaming around as I wanted. Constantly respawning Fallen make exploration more of a chore as well. Maybe it's just because it's in beta but I'm really disappointed with that so far. I want to explore this seemingly vast and open world.
The character customization is simple, but pretty solid. Gear is varied and generally cool looking. Emblems and armor colors are standard but a nice touch nonetheless. I'm guessing crafting is going to be in the full game. Looking forward to seeing its depth. I like the merchant system, though I feel glimmer drops should be more frequent.
Onto story...I'm somewhat mixed. I like the world so far, I really do, but I'm just not getting enough of it. Again, this may be due to just having played a beta, but the game desperately needs more fleshing out. As I take it, the player is a formerly dead person resurrected to fight for the Traveler against something called the darkness. I have no idea who or what the Traveler or what the Darkness is, or why I should even care about them. What exactly happened to Earth? Who are the Fallen and why do they want to murder me? How the hell did Peter Dinklage bot get down to Earth and revive me with space magic? I know Bungie likes subtle storytelling but I need more.
I've voiced my opinions on PvP here before but I really don't care for it at all. There's the obvious comparison to be made to Halo, and I'll avoid it and look at Destiny as its own thing. It allows players to bring in their own character, weapons and gear; imo this is a blessing and a curse. I like seeing my dude donging other dudes, but there's a glaring issue with this. I have no idea what my enemies are capable of. Do they have a shotgun that can one-shot me? Or is their super up, meaning I can't sit in one place for more than 3 seconds without worrying about a Titan dropping the D on me or a Hunter/Warlock instagibbing me from 20 feet away? In the case of the Iron Banner, maybe it's just a level 4 scrub who owns nothing but a 20 atk pea shooter. I want equal starts. I want to know if my enemy has their instakill ability just sitting in their back pocket. I want predictability. Destiny PvP gives me none of these things, and leaves me with an inconsistent mess. Vehicles are incredibly strong, leaving very little counterplay if one's super isn't up. The maps are solid enough and direct the flow of combat well. The announcer needs some work. The modes are standard fare, from what we've seen. Matchmaking is poor; many games result in lopsided blowouts.
And I guess I'll end with miscellaneous stuff. The OST is great as always. Marty is still the GOAT. UI is solid. Minor issue with HUD (though this is a PS4 specific issue) - PSN notifications pop up right where the radar is, blocking it out for a few seconds. I don't like losing all my special ammo when changing weapons, especially in PvP. The sparrow is a fun idea. Traveling between worlds takes way too long; I wish I could choose where I went next from where I currently was, rather than having to go back into orbit.
In the end, what I've played has been really solid, especially PvE. It's no Halo, but Bungie did a great job with their idea of a open world FPS. I'll definitely be there in the fall. Hopefully the game has a significant amount of content.