|Definitely get an XBox controller for your PC to play this game. Otherwise you will be replacing your keyboard with great frequency just because of two keys for the flippers. It is an addictive game just like any pinball table. The base package that is free on Steam has one table that is free and is probably the best of all of the tables that are available to date. The publisher makes money off of you buying additional tables for the base engine. At the moment there are 6 4-table packages and 6 single-table packages that sells for about $10 and $3 respectively.
I have a 4 year old i7 with 4 cores and hyper threading on Windows 7 and a Nvidia GTX570. I play the game with the max graphics turned on and haven't seen any problems with glitches or playability.
As for the game itself, if you have ever played the Nintindo Wii Pinball games, you are going to be slightly disappointed with this one. The Wil Pinball games are more complex and the visual controls are more mature. But if you have never played on the Wil, you will find that this is a very good simulator for pinball. You have a variety of tables you can buy, the tables are pretty complex on the rules for how you score and play, and the gravity of the ball seems realistic.
The only negative I have is that it seems that all of the tables are really the same pattern with just a few modifications. Some of the newer single table packages appear to be deviating from the base layout. Paranormal is an example of one that significantly deviates. This is a fairly new game as of August 2013 and I am hoping that more tables with a bit more complexity and a variety of layouts will come out over time.
Admittedly, I haven't played online or explored any of the competitive aspects of the game.