Man, unless those "wrist" guards are made out of balsa wood, they must weight at least like 80Kg each. He may be a muscular alien but damn, don't you think it'll slow him down considerably?
Also the model has an overall messy feel (due to ZBrush overkill, if you ask me). Look at the pauldrons, where that little skull is. That's a very messy area. I think you wanted to give the illusion of worn armor, but I don't feel that. And that amulet he's wearing, well sorry but looks pathetic, it's very badly modeled.
And that ear...well sorry that I forgot to show you how I think a good ear should look, but I'll show you now. I hate to give my work as an example, but it's the only thing I got right now. This is how I think a good ear should look like:
Look at it, it has VOLUME. That's what I was talking about. Your ear looks more like a messed up plane in which you dug ditches. And that perfectly sharp corner at the end and those strait outlines personally don't work at all imo.
And the area around the neck is also messy...the neck muscles are straight, running from the back of the ear to the upper part of the sternum. They don't bend so exaggerated like that.
I think you jumped in zbrush and detailing it way too early. I bet you didn't even set the topology correctly to mimic the muscle flow before you exported it to zbrush.