Depends on what you want to do! Amongst apps I really like now:
- Scrivener
- Tweetbot
- Logic Pro X (oh my Logic...)
But TBH for the MOST part you aren't going to find a bunch of stuff your MBPr can do that your PC laptop couldn't. It's just a better experience overall. My REAL suggestion? Learn ALL the shortcuts. This thing is crazy with workflow and window management.