Other than generically saying an A2 is better than the worst upconvertor and (probably) not as good as the best, you'll have to find someone who owns both your chosen "regular upconverter" and an A2 to make comparisons. My hunch is that they would be in the same ballpark, but that's just a hunch. Myself, I would let price decide.
Be aware that an A2 will boot up slower than a standard DVD player, if that's of concern to you. Also, if you have a fancy universal remote control and are using macros, you won't find a discrete power on and discrete power off code for an A2. "Play + Stop" substitutes for discrete power on. And "Play + Stop + PowerToggle" substitutes for discrete power off. However, the A2's 30 second boot time can mess you up with these substitute commands in certain circumstances.
The OEM remote control for the A2 sucks. But then, every OEM remote control for every DVD player sucks. So it's a wash in that department.
I wouldn't trade my A2 for anything less than an expensive Oppo upconverter. And maybe not even then. But that's purely subjective unsupported opinion on my part.