A cursory look on Notebookcheck on last year's model tells me the 1080p display was a lot better than the Eluktronic's model they compared it against. And if Dell is using the same vendor, it's an AU Optronics panel which as far as I can tell, they're a decent enough supplier.
I don't really care about 2.5G Ethernet since I rarely use that much bandwidth unless it's a backup to my NAS (and even then file system overhead tanks it). I'm pretty sure most people still have no real need to go to 2.5G
I don't see a point in an IR camera other than for Windows Hello. Though it looks like Alienware m15 doesn't have any sort of Windows Hello supported hardware. As much as I like the fingerprint reader on the last two laptops I've used, I don't really see no Windows Hello hardware support a deal breaker.