Just played it, and here's what I have to say:
I just played a game today with my friends that I usually play Talisman (3rd edition) with. We all agreed that Relic is a much better, and much more fun, game. My friends took the Tech Priest and Space Marine, while I grabbed the Cannoness. I didn't use her special addition of encounter cards until late in the game, starting off slower than them (they got tons of wargear quickly), but once I got rolling, I killed everything in my path. We played the starter game, and each of us was a single turn away from winning the end, but I won by a single turn. It is very similar to Talisman, but adds a few things (remember, I've only played Talisman 3rd):
1: You get to choose which skill stat you'd like to fight enemies in, but sometimes random enemies from the other two groups show up-so you have some control, but not all the control.
2:Explosions can turn an easy win into a struggle: I had an 8 in cunning with a needle pistol (+1), facing a level 1 opponent: my buddy exploded and then rolled a 5 in addition for the enemy, so my level 1 turned into a level 12 against my level 8. I still rolled a 5 and killed it, but it shouldn't have been as hard as it was.
3: No spell cards. Instead you get powers that have an ability OR let you substitute a power's number for a dice roll. Need to roll a 4 and you have a 4 power in your hand? Discard it for that auto-4. Gives much more player control.
4: No attacking each other. You can't fully assault the other players, as you all work for the Imperium of Man, but you can play cards that negatively affect your opponents, and potentially allow you to steal from them.
5: Missions-you start with a mission, and completing it gives you more experience towards gaining a Relic. Missions range from easy to hard, and may involve stealing something from an opponent or exterminating a planet.
TL;DR-Relic allows for more player control than Talisman and is quite a bit more fun. Oh, and I highly recommend it!!
Also, I'm gonna start work on custom character cards for it, such as a Blood Angel
SM: special ability allows him to use his "red thirst" to discard a trophy to gain a life, a Grey Knight who gains +2 against all Daemon opponents, and a Vindicare assassin that starts with the sniper rifle and can choose to re-roll his attack die. Those are the only ones I've got so far, but I HAVE only played a single game and only had the game open a few hours...gimme time