Just about everything is going to be way better than what you have. Better handling, better, towing, better stereo, more power, smoother riding/driving, larger box. With the 5.7 Hemi, you probably will get the same fuel economy.
There really aren't many take-aways ...except for:
1) Size: the Ram is about 25% larger than your truck. Full-sized trucks have become mega-trucks compared to older models. That is one significant take-away in my mind with the Ram. Doesn't bother most owners, but what you have is one of the last years of the older/smaller pickups. When I drive my older pre-2000 GMC short box, the slightly smaller size just feels better. Visibility over the hood and out the rear is noticably better The older GM is easier to park, easier to load items into, easier to reach over the box side, easier to get in and out of. If you commute, than the slightly smaller trucks are easier to put where you want them. But overall it comes down to personal taste. Any newer truck is going to be larger so you can't really get away from it. Sometimes the larger size of the Ram comes in handy.
2) Electronic Integration: Newer cars and trucks have more electronics. As long as they work ok, everything is good. Usually they do. Ultimately failures or snafu's will occur. When they do life's a bitc#. And when items like large LCD's flake out, they can be expensive to repair/replace. Mfgrs are putting all kinds of 'gimmicks' onto the LCD's/computers that for the most part don't add to ownership, and may even be take-aways.
3) Interior Fabrics: Now I get to rant on another one of my peeves. If the truck you are looking at has leather, than you'll probably love it. But interior fabrics on trucks (and modern cars too) generally have gotten continually worse (quite a bit worse) since the early 90's. IMO. Interior fabrics used to be plush, smooth and comfortable on your skin. Now the type of weave they use is harsh, scratchy and cheap. But leathers are available which are usually pretty good grade. If your prospective pickup has crappy cloth, companies like Katzkins sell high quality leather replacement seatcovers that fit perfect. They would need to be installed (they're not slip-overs). Probably better overall quality than the OEM covers.
4) Price: Right now is a terrible time to buy a used pickup. Prices are at an all-time high. But if you've found a 'cherry' example, for the right price, maybe you should jump on it.
I wanted to buy a new Chevy in the worst way, but comparing to the Ram one could see (at the time -- before the new Chevy tk) ....GM just hadn't done their homework as well. A lot of that has been corrected with Chevy's new pickup. GM is going to re-do the funky front end styling on their new pickup soon. Make it more streamlined and less 'busy' looking.
If you haven't been able to decide by now, maybe that's saying you aren't 'sold' on the new Rams. Therefore perhaps you should keep your existing p/u, or buy another (better/) example of what you have ....and keep the money in the bank.
It'll have a lot more power, about the same mileage, tow rating is unique for every configuration and can be googled, every major seat cover brand makes fitted seat covers for them... 
