Opinions on AMD A8-4555m

How does this APU perform compared to intel counterparts? And more important, which Intel CPUs are its counterparts? I ask this because CPUBoss shows even i3s utterly destroying this A8 whereas game-debate seems to suggest that its competitors are to be found within the i5s. Also, I don't know if everything's OK with game-debate: how does their percentage index work? They put the FX-8350 as 22% better than the 3570k in gaming. Is that really the case? I know it's arguably better but 22% looks like a lot to me.

Depends on which games they tested. A lot of review sites are partial to intel because they make a profit as well doing so. A8 has a better integrated gpu and you can actually play games and is about as strong as a hd 4600 from an i7 4770 (which isn't nearly enough for big resolutions and high quality settings and textures). As a cpu only it should be better than an i3 in mostly everything since it's an actual quad core, not a dual core with hyperthreading. It definitely beats the intel i5s counterparts in gaming with it's better integrated GPU.

right now amd has the leg up in the integrated graphics area but intel still on top when it comes to processing performance and power efficiency. 

You can't beat a decent graphics processor and a cpu in the same package at a reasonable price and good power efficiency. Not even with say an i5 + a 7750. If you can afford something better then get an fx vishera and a dedicated card.

My issues with this particular model descend from the fact that this is a laptop APU without a definite price (apparently), so I would have liked to have a better overview on how this may or may not be the best choice against a certain intel counterpart. Counterpart which I am having difficulty to define, due to the fact that I would need to consider two laptops as identical as they can get aside from the CPU since most of these laptop CPUs are not available on the market.

Let me rephrase: The i3 would only beat the A8 if it had a good dedicated card to power it. Otherwise the A8 is better.