Well I cannot help with that specific loco, but if it helps any in regards to quality… I have an Atlas Master GP38 from approximately 2006. Standard factory installed decoder. It runs beautifully. Detail is quite high. I got mine undec so I can’t say if decorated models have any parts needing to be added after purchase.
But that GP38, my MP15, and C420 are all my best runners from Atlas circa 2004-2008. Safe to assume quality has only gone up. I’ve not heard of any complaints (thinking comparatively to BLI loco lately).
I cannot think of any real “beware of” aspects worth mentioning. The typical grabs are metal, railings are plastic. Antennas that came with mine were plastic (I upgraded to brass for durability). Par for the course type things that fall under personal preference.