As a college student who's owned a non-Retina 2012 13" Macbook Pro and now owns a 2013 13" rMBP, I'm betting I can offer some stellar advice
Once you go Retina, you never go back. Every time I look at my old Macbook's display, well, it hurts. It's terrible. I'm shocked I ever used that thing, especially for looking at images or watching videos.
Haswell is absolutely worth it. I've seen the battery-remaining time estimated at 13:xx before (of course it was mostly idling, but still, way more than I ever got with the 2012). It doesn't fare too well with games in Windows (bootcamp), though... Hopefully you're not getting this for gaming, otherwise you'd be looking at the ~$2600+ 15" Macbook Pro. Anyway, I haven't been back to school since I got this thing, but the thinking is I can leave the charger in the dorm room.
BestBuy's Memorial Day Weekend sale, combined with their student discount of $150 for all Macbooks, was the cheapest I had ever seen current-gen Macbooks. So I hopped on it. Originally I was going to wait for Apple's July-September back to school promo, but the $100 giftcard and $100 student discount couldn't beat the ~$300 (all cash, mind you) I saved @BestBuy. For once, they really were the
best buy. I believe the student discount is year-round, so you just have to wait for BestBuy to put the Macbooks on general sale, which is actually quite often...
The caveat was I had to settle for a "pre-made" Macbook. I was going to go custom (max out the RAM), but determined the savings were too good. Lo and behold, 8GB is plenty for me. To help you figure out how much RAM you need, open up the apps you'll usually have open (or if you're feeling it, open all the apps you possibly can

), then open Activity Monitor. Go to the Memory tab, and see what "Wired Memory" looks like. That's, in layman's terms, the RAM that is actually in use. The rest is used to boost overall performance, but the gain is marginal when you have an SSD, especially a PCIe SSD like the one in rMBPs.
Anyway, I'm hard-pressed to use much more than 1GB of RAM when counting only Wired. As with the medical field, recommendations vary slightly by doctor, but this physician would recommend a ratio of about 1:4 for Wired Memory to Physical Memory (total RAM in your computer). For example, if, when all your apps are open, you're using around 2GB Wired, 8GB of RAM would be good to go with. If you're using closer to 4GB wired, I'd go 16GB. While 16GB is rarely necessary, OS X puts all the RAM it has to use to speed things up, so you really can't have "too much" RAM. Especially when the RAM isn't user-upgradeable. You can't just buy RAM and throw it in (although you can with the non-Retina Macbook Pro).
In fact, not to go on a rant, but without virtual machines or some intense professional work (ie. Photoshop, Final Cut Pro, etc.), there's virtually no way you'd ever need more than 8GB (at least with today's OS X and applications).
Some other things to consider vs the 2012 Macbook Pro:
- The speakers are
incredibly better on the Retina Macbooks. Much louder, clearer, better bass response.
- The 2012 Macbook Pro is a laptop. The rMBPs are
ultrabooks. Lugging around that 2012 Macbook all the time sucked immensely.
- Adapters, anyone? Not with the rMBP, because it actually has an HDMI port. Yeah, that thing that's been on virtually EVERY laptop since 2011? It's not on the 2012 Macbook Pro. You'd have to buy a mini-displayport-to-HDMI adapter, which uses its only Thunderbolt port.
- Nothing obnoxious, either. You may think the pulsing light on the front of the 2012 Macbook Pro is "cool", but really it's just the reason you have to get out of your bed to turn the thing around so you don't see it when you're trying to sleep in your otherwise pitch-black room. If it's bright enough to see during the day, how bright do you think it is at night? Very. And how'd you like to hear the SuperDrive make its obnoxious "er eeeer errr"/"Is there a disc inside me?" noise every time you go to use your Macbook? It gets annoying. It turns heads in class (and not in the good way).
I spent way too much time on this post... Hopefully it helps you, though.