I've done a couple posts here and there that focused on critiquing specific things I took umbrage with, so it's well past time I spend a bit writing up how I feel about the game (and it's largely positive!). While I generally seem harsh with my criticism, it's intended to be blunt and honest, not a sign of disliking the game itself.
First things first... it runs beautifully on my system, for an alpha client. I'm not running a toaster anymore (though I did fondly name it Battletoaster), but I'm also not running a high-end fully optimized setup. I'm regularly getting smooth 45 frames per second (my eyes are kinda bad, so there's a gap between a lil above 30 fps and 120 fps that I just don't process fully), though it does dip when in a 3 person kill-team and two of us are rocking heavy bolters (which is an absolute blast, pun intended), at the lowest I hit about 15 frames per second, and... well... there was a lot going on. With the "ooo pretty" out of the way, on to...
Balance. I will avoid beating the dead horse as I've made my feelings about shields clear. Instead, I'm going to cover the good. And that's plentiful. No matter what ranged weapon I choose this build, it can fill a role in my playstyle. Grenade launcher? Area denial and debuff prior to jet-packing in and hacking things to bits or laying on obscene amounts of dakka from another weapon. Heavy bolter? Park myself behind a choke point and chew everything up (which gets really entertaining in coop where there are two of you doing this, talk about overlapping fields of fire!). Heavy flamer? Roast those [expletive deleted] nurglings and serve 'em up. Even the humble lasgun gets a chance to shine; and none of them feel inherently "better" or "worse" than others, they all suit a particular style of play. And that right there is where Martyr really starts to truly shine. While I'm disappointed I haven't found an upgraded chainsword, in group play it is no longer an irrelevant piece of equipment--someone debuffs/stuns a fleshy foe, and I ram the thing in its gut until it stops twitching. Or I shield charge through a clump of warlocks. Etc, etc. It's not often that I get to feel like a particularly relevant party member, because in many ARPGs players become very good at being self-sufficient; not to mention gear-twinking causing large gaps in power between similarly leveled players. Not so much in this build, and that's a good thing. No, that's a great thing.
Outside of the thunder hammer and multi-melta, I've dabbled with just about everything available to the Crusader. The passive skills take some time to really "show", but when they're noticable they're really noticable, and make enough of a difference to change how you approach a room.
For example: currently, with my tank, I'm (finally) tanky enough with the addition of a refractor field I can park myself outside of cover to provide supporting fire. This is really surprisingly useful in coop when coupled with my jump pack, as that extra health means I can jump to flank enemies and pour fire on while they're focused on other players, and then retreat quickly (thanks to the bonus focus) when their attention turns to me. This evening that meant having a blast doing things one reads about in the novels (because honestly, jump packs have always been underwhelming in the tabletop)--standing firm against a not-insignificant daemon, mooshing renegades under my (apparently weighty) boots, and generally causing a ruckus. Spot on.
Finally, your netcode. There are very, very few games forgiving enough of my net's latency that I can contribute, let alone survive in... and none of them are alphas. There are some hiccups, no doubt. I had to force-quit in order to resynch a few times tonight, but given that I was able to binge three or four solid hours of coop in CR3 content (which I cannot solo yet) without a single disconnect, it's pretty solid. There wasn't much in the way of rubberbanding, and outside of those desynchs I didn't experience the usual "mobs are immune to my attacks/I am dead before I even saw the enemy" issues.
So, all in all, a very positive experience and I'm looking forward to seeing what comes from it in the future; and I will definitely be springing for copies to give to friends in the coming months.