It's really easy to use and you can place an order directly from the software. Not sure if eagle has that or not.
No Eagle is not locked into any PCB manufacturer. Instead it allows you to generate the industry-standard Gerber files which can go to nearly any vendor. Which is great because you can use services like BatchPCB or Seeedstudio. Both of those are at least half the cost of Pad2Pad.
The majority of the Hobbyist community uses either Eagle or gEDA. Both are free. Both are multi-platform. Both generate industry-standard files. Because they are so widely used, there are tons of tutorials and forums available to help get over their slightly higher learning curve.