I have the early 2013 MacBook Pro. It is still pretty fast. Nothing I saw today makes me happy to upgrade as a developer. Sure it's lighter and thinner and HUUGE trackpad that's a nice to have when I'm traveling. But the TouchBar requires me to look down at my keyboard which slows me down. And they can't even leave the keyboard itself alone with the terrible butterfly implementation coming over from the 12" MacBook.…
I have no idea with the idea of MagSafe, but on my Retina MacBook Pro (also early 2013), it's become extremely finicky. About 20% of the time, it just doesn't charge. I just have to connect and disconnect it a few times and eventually it works.
Sometimes little bits of magnetic debris can get stuck in the computer side, e.g. iron filings, staples, etc. You can try to get these out with Blu-Tack or similar if the q-tip doesn’t cut it.