Thought I would add my own anecdotal experience, coming from a 13 non-TB MacBook Pro (I upgraded to 16GB of RAM but kept everything else stock.)
Obviously, most of the battery life concerns are coming from the TB variety, but I believe that if you need to upgrade and need decent performance and great battery life then the non-tb is a very viable option.
Benchmarks put this model within 5-10% of the TB model, yet I have consistently been getting fantastic battery life. I am in the film industry and bought this to upgrade from my 2012 15" MBP. We were going to be on the road in foreign countries and I wanted something much more portable. My job is a writer and director so I wanted great battery life to read and write scripts while on an airplane, but also be able to review daily footage and do some light 4k editing when needed.
So far, I have been very impressed with the non-tb model. I recently flew from LA-->Atlanta-->Paris-->Berlin, working in-air and on layovers. This machine lasted the entire journey on a single charge- I believe I landed in Berlin with about 30% left. Granted, I was not working the entire time, but I felt this battery life was more than adequate. Workload included email, iMessage, reviewing cuts of movies in QT, Google Docs, Final Draft, and Safari.
Since starting production here in Germany, I have had no problem quickly transferring footage to the machine from multiple hard drives for review (I bought a $30 SD and 3xUSB A dongle before I left) and no problems playing back 4k footage. (Not to mention the color accuracy on this screen is incredible)
I understand some of the frustration on this forum, but my personal experience has left me very impressed with this machine. The size and weight have made a considerable difference for me constantly moving from location to location - and the battery life has remained impressive (around 10-11 hours) - even in the freezing temperatures we have been experiencing here.
My few complaints? I am still getting used to the keyboard, and on occasion, it seems that the trackpad will fail to recognize a click with its haptic engine (I think because of the palm rejection software). However, I am quickly adjusting to both.
The price? Yeah - it certainly is a bit steep. But I felt like I got a good deal. I found the custom 16GB model at BHPhoto for $100 off without tax, plus I happened to open a new credit card with a $150 signing bonus. All in all, I would gladly pay $1450 for this machine again.
I guess what I am saying is, if you have to upgrade now, and don't need a 4-core machine, give a serious look at the non-tb version. I think it just might be the best combo of speed, portability, design and battery life offered by any manufacturer at the moment.