I'm pretty sure that model has the forged receivers. It's as basic as you can get with an AR, an entry level model. And you're right, a few years back they did make them with the cast receivers, and there were some problems. But Oly learned from that and moved on to the forged receivers in the Plinkers.
I've got quite a few friends who swear by their Oly AR's, and I've shot a few of their's, too. Looks just like any other AR, operates the same way, fires the same rounds, and with each trigger pull. No, it's not a top-shelf model, but at that price, it wasn't designed to be.
I think you hit it right on the head. For something that you can use for plinking, some target shooting, and even for HD, that's pretty affordable.
Another option you have, buy a kit and put an AR together. That way, you get to see how it all fits and works together, you control the quality of assembly, you learn a lot about the gun and hot to fix it, and it's fun. Check out these sites:
Del-ton AR kits
Model 1 Sales
DPMS AR Kit
All you would need to do is go to your local gun shop and buy a AR Lower Receiver, everything else you need, as far as parts, are in the kit. Just an idea.
But if you already have money on the Oly, there really isn't anything wrong with that one. Don't worry about the naysayers and brand-jockeys out there. As long as it works when you want it to work, and does what you want it to do, that's all that should matter. Enjoy it and welcome to the disease.