HTC is a solid manufacturer that has been around for quite some time, but has up until not all that long ago made phones that got braded by Telcos... though you may not have heard of them... but if you have seen SmartPhones (particularly up until last year) WinMo phones, many were HTC.
That being said, the Eris is not in the same league as the Droid. Not in power, resolution, quality or any other standard... but that should be obvious by the price alone... and it is true.
The Droid is currently the best Android device on the market (and arguably I will say the best phone on market) right now.
But if you just want to make calls, and don't necessarily need the best, strongest phone and are just making phones calls and texting, then the Eris will suffice.