The graphics in the game are adequate and sometimes even better than that. They're not going for console quality here, but more the cartoony type of graphics you see in many casual games these days. That said, the graphics are generally clear and it's easy to tell what everything is. The land is clearly layered so you can see how many you have to move when you're sculpting, and the characters have a simple look that I enjoy, but others might feel differently. Animations are pretty basic but work well, and I've found the responsiveness of the game to be pretty good, although when sculpting it can be difficult to tell if the land's about to snap back on you or not. There are some nice touches to the shrines and some other parts of the game with nice glows, animations and colors. Again, the graphics are fine for what the game is (at least so far) but don't knock your socks off, and that's not what they're trying to do. This is a more casual game, and the graphics fit that.
The sound is pretty minimal, but again adequate for what's happening. You get working sounds when your followers are building things, they speak a Sim-like gibberish, and there are sounds when things are completed or other special events occur. They're nice and well done, but mostly serve to keep the game from being silent and provide a little bit of atmosphere. I believe there are different sounds for different events (a follower leaving their house, starting work on a house, finishing one, belief needing harvesting, etc.) but by the time you get a decent number of followers, there's so much going on it's hard to tell one sound from another, so they're not really helpful in that way.
Godus is available on Steam only for $20; for that you get the beta, any updates and then the full game when it's released, supposedly sometime this year. If you're asking me about buying the game as it is now, I'd say it's tough to justify the price, there's just not enough there there yet. So if you buy now you're paying some to play now, but your'e mostly betting on the future. How you feel about that depends on how likely you think the game is to deliver on its promises. There are plenty of skeptics out there, as Molyneux has disappointed before, and many people think consistently for several years.
On the other hand, this is the guy who made Populous and Black & White, so the potential is certainly there. I can't tell you what to do, but you can read the forums and maybe even wait for a sale, there was one this fall and who knows, may be another one. There's also expectation that a new beta might be upcoming as the developers have been silent for awhile and there hasn't been a significant update in awhile, so maybe you can wait for that if you're still on the fence.
As you can tell, I'm somewhat conflicted by this game, even at this somewhat early state. While I easily spent many hours playing, the more I played the less interested I got. The only thing that seemed to get harder was terraforming, and expanding my civilization didn't lead to enough payoffs for me to stay engaged as time went on. The lack of clarity in what I needed to do to keep advancing my people didn't help. There's a good game in here, but whether the developers will dig it out remains to be seen. Meanwhile, I think I'll probably keep plugging away while waiting for a new beta that will hopefully add some clarity to where exactly we're heading and whether the game's initial promise will be realized. I like god games, I really do, and it's nice to see something old become new again and provide some variety to the gaming landscape, but the next 59% of Godus has some work to do to be that game that so many hoped it would be.