I recently got my hands on a copy of Shadowrun as well, and I really enjoy the overall feel of the game. It's rife with "layers upon layers" (as the good folks at RPPR would say) and the setting lends itself well to a deep, intrigue filled story. The rules are a bit...in depth, and I can imagine you'd have to run the game a couple of times to really pick up on the intricacies of the system. From experience with previous editions, I will add that the game is brutal, a couple of bad choices can get PC's dead with a quickness. Not a bad deal, and needed for the flavor. After all, if running the shadows were easy, everyone would probably do it.
A couple of recommendations from experiences I've had running previous editions:
1) Don't let the rules bog down the game. There are a lot of rules for a lot of situations, and unless you're running it for a convention, focus on the plot and making that work. If you have to, make something fair up on the fly, note the rule you forgot, and look it up later.
2) When writing for Shadowrun, the city / place your game will occupy up first. Pick your NPC's, factions in the city, and local powers before you sit down to write your first run. Build these up first, and make sure that everything your PC's do have some ripple effect. Everything and everyone living in such close proximity as a sprawl is connected, and therefore every major event in the city is bound to have fallout. If you do this, your players will feel like they are really accomplishing, not just getting EXP. I'm sorry, that's Karma in this system.
3) When you develop NPC's give them a few goals, and decide how open they are about accomplishing these objectives. Runners should have to struggle and do their homework to figure out what people actually want, it’s not a game of spoon-feeding the PC’s.
4) Make sure that all your NPC’s have that spark of life. It takes doing, but in Shadowrun contacts are important. Success can really be based on who you know, and of course, how well you know them.
Anyways, it’s a great game in a lot of ways, (but make sure you have PLENTY of D6’s around) and I hope this helps anybody looking to get into a shadowrun game.