I've been using True20 for a weekly game I've been running since the beginning of September, and I have to say my group and I love it. However, this was only after an extensive play-testing period and making some changes to the system...
First, we increased the threshold for each of the levels of hurtitude with the damage save (Hurt if you fail by 1-9, Wounded from 10-14, Disabled at 15-19, Dying at 20+), which make fights a little less...well, deadly.
Also, by using the revised/errata'd version of the rules, things are even less deadly (mainly because you can be Wounded infinite times before getting Disabled, assuming you can keep rolling 20s on your Toughness save, just like with being Hurt).
As to the style of campaign it's been so far...well, I'll describe the major things that have happened; (note; this campaign actually has two sets of PCs and one set of players, an experiment which has been going quite well)
* The PCs went to visit a wizard for information, only to have information forced out of them magically, and then be swarmed by the traitorous wizard's minions.
* They made a daring journey through the wilderness, attacked by various evil spirits and unfriendly plants and so forth.
* They fought their way through the ruins of a goblin-inhabited dwarf-hold, eventually fighting the Goblin King himself.
* Much later, they found themselves in a town being opressed by the monks at the local abbey who owned the land; as well, creepy supernatural stuff was going on; ultimately, they uncovered some of the monks as evil cultists and saved the town
As for the next adventure, the PCs will likely be searching the half-flooded subterranean part of a large city for an artifact.
Oh, and I might as well describe the party, too...
Aelfgrim (aka Callondir Eredhil or somesuch): A tall, lanky fellow of a decidedly brooding nature, who just happens to be the descendant of an ancient hero, who has made it his quest to reassemble his ancestor's sword. He's a very skilled warrior, and a good leader and diplomat.
Kjiolik: An elf from the wild north, Kjiolik is a master of the magic of nature, specializing in ice magic; as well, he's a sneaky bastard, and could potentially survive indefinitely in the wild. He doesn't really have a mission, but instead follows his companions and does what he feels is right.
Sigrath: a skilled archer and childhood friend of Aelfgrim, Sigrath has harbored a grudge against demons ever since his parents were killed by one; he has made it his life's work to hunt them and those that would summon them.
Alamir: once a man-at-arms, the muscle-bound half-elf Alamir promoted himself to 'knight errant' when he got sick of guarding a castle all day every day. He is a brave warrior and has a winning smile, and can be quite intimidating when need be.
Ahadhran: a cynical, anti-social elf, Ahadhran gave up on mankind a long, long time ago. However, his pure hatred of orcs and trolls and other evil creatures has driven him to save idiot humans on more than one occasion. He is a skilled scout, archer, and a master of the surprise-attack.
Caranir: as the third son of a nobleman, Caranir knew he wouldn't ever have to actually rule anything, so he spent most of his youth with his face buried in books. As he got older, he was allowed into deeper and darker parts of libraries, and began reading tomes that contained actual magic. When he realized what knowledge and power there was to be gotten out in the world, he left home, travelling from city to city studying in the great libraries of every nation. As time progressed, he began travelling into wilder and more dangerous places, finally resulting in his meeting with a particularly treacherous wizard, who he has since sworn revenge against. Also, he now has a servant...errr...apprentice by the name of Norri.
Long story short, True20 has served us better than D&D ever would have for this kind of campaign, if only I'm too busy as a GM to spend an hour making each spellcaster NPC, and most of the PCs would have been, well, hard to build in D&D without being at a severe disadvantage or having completely 'wrong' abilities...I'm lookin' at you, Alamir and Kjiolik.
Anyway, it's just a very fun, no-hassle sort of game, so long as you're the kind of GM that make judgement calls that satisfy their players. It's especially good if you're the kind of GM that's impatient, and likes to cram a lot of fighting, roleplaying, and story all into the same session without losing out on quality or having to have super-human math skills and players that are just as good.