You're living in a fantasy land if you think Halo 4 looks better than this. I agree H4 is a gorgeous game but 5 is clearly superior.
On top of this, he is basing his opinion on a YouTube video; YouTube has made judging graphics this generation a cluster fuck.
I'll post them again, this is the same footage but straight from Microsoft and at 15,000+kbps bitrate:
http://news.xbox.com/api/mediacart/download/a8a8850b296e405aba15ab328b5dde47
http://news.xbox.com/api/mediacart/download/f94d3327744749afb504ab0d202a6a20
Judging graphics with YouTube is an awful thing to do, you shouldn't even be allowed to call it B-Roll once it is on YouTube as it implies high quality.
Compare this:
https://www.youtube.com/watch?v=ns0AWhrEmVo
to this:
http://www.gamersyde.com/download_forza_motorsport_6_e3_direct_feed_gameplay-35017_en.html