Hiya Bao.
1. That's not a bad way to sum it up. It's an MMO, so despite differences in art and mechanics, it still follows the kill-loot-level paradigm most other games do. Past that, enjoyment of VG's gameplay is to some extent a personal thing.
2. I can't answer the PVP, though from what I read I get the impression that PVP in Vanguard could use a bit of work. PVE works pretty much like it does everywhere else. Find mob, fight mob, kill mob.
I can't comment on more specific things like waiting or competing for spawns because I play mostly on the Test server, which is considered to be heaving when there are 40 players on at one time - competition isn't really an issue there.
3. The three spheres are only technically independent; in order to get the most out of each you'll find you need competence in one or more of the other two. Crafting, for instance: you can level up more or less in a vacuum, but in order to make good items you'll need harvested resources which, in most cases, are easier to obtain at higher levels if you have decent adventuring skills... or folk who can supply you. In that respect Vanguard is, again, like most other games out there; I think the vaunted independence of the spheres has created more misapprehensions than simply saying you'd need a mix of all 3 to get the most out of each one. (A single char doesn't *have* to be competent in all three spheres - having friends who can fill in your gaps works almost as well.)
That said, many people are *just* adventurers, quite a few are *just* crafters, and there are a number of people who do nothing but diplomacy, all without requiring dozens of levels in any other sphere. Having a good support network helps, but that's the case in any game.
4. The last few patches have had pretty huge effects on stability for many setups (though as usual there are a few who have, paradoxically, suffered) - I had the client running all day yesterday, for instance, through numerous char changes and long travels, and didn't crash once. A few weeks back I could rely on crashing at least 2-3 times a day, usually many more.
That said, there are still quite a few things to iron out, some of which are due to be patched to the test server pretty soon. It's definitely improving. Whether it's playable for you or whether it's too buggy depends partly on your rig (some are more prone to issues than others, and you can't usually tell till you try), partly on your own tolerance for bugs, and partly on your playstyle.
I'm having a good time in Vanguard and have been since beta, but I also made a conscious decision to play
despite the bugs and issues I knew were there - friends of mine, conversely, made the decision to stop playing until things were smoother for them.
To be blunt, unless the cost is negligible to you I would advise waiting a month or three before picking up Vanguard. There's a ton of work being done, including various things to make the initial Vanguard experience a little easier (which may not be an issue for an experienced MMO player), and we may well see some kind of free trial at some point.
On the other hand, if you can absorb the cost and don't mind taking the risk that you won't like the game, or if you're pretty sure already that you *will* like the game... come join us. Despite the bad press and the game's now laughable reputation, it's neither as good as it was once hyped to be (what is?) nor nearly as bad as some are saying.
Our dozen or so servers are going to be merged into a third of that number in the next few weeks, which is going to cause some upheaval and might be worth noting; however, I haven't seen an ETA on that.