The Cobra is a very good multipurpose ship. I ran with it for quite awhile. It has a distinct cargo capacity and speed advantage over an adder. The rest of the stats end up being minor upgrades over the adder as well (power plant, jump range, capacitor).
The big thing to consider though is that if you choose to start upgrading it, that cost can easily go into the millions itself. Getting a 4A frame shift drive itself is 1.6 mil…and I highly recommend the highest frame shift drive at a minimum.
Of course, one core mine and you might be able to do all sorts of upgrades