My Amazon Slag showed up.
First impression: His robot mode is impressively large. Grimlock is just as big, but it seems less unusual for him.
One of his knee ratchets immediately broke. Not overly concerned as the joint is still plenty tight and functional, was just a bit of a disappointment. I'd heard of several people having this problem with Grimlock, but hadn't noticed any reports of it with Slag.
He is good, but a bit of a let down after Grimlock. Grimlock looks excellent and accurate in both modes, has a transformation that is more or less G1 accurate, and that is fast and fun with 0 fiddle.
Slag has the looks in both mode, but his transformation leaves a bit to be desired, I find the tabs on the side of the tail extension and the wing tabs a bit fiddly. It's just not as smooth and satisfying as Grimlock.
The back legs are a bit dinky looking as well.