I have owned a rMB since the original one came out. Up until today, it was the best Mac I've ever owned. I bought it as a secondary machine to my primary rMBP (first generation) of which I did most of my heavy lifting on, including web development, which is my day job. However, performance just isn't there. You can feel the sluggishness when doing anything other than light tasks like browsing the web or mail.
That being said, the rMB is a fantastically portable machine. You can throw it in a bag and not even feel it's there. But I wouldn't recommend it as your daily driver. Great secondary machine, not a primary machine at all. Fast forward to today, I just received my 13" rMBPT. I love this machine. It's only a pound heavier than the rMB, but has many times the performance and features. This will be my new daily driver.