60fps automatically improves things, if all else remains the same, but that is never the case. 60fps usually comes at a hefty cost, and the additional things a lower frame rate enables can just as easily improve gameplay. Eg, better resolution, physics, larger levels, more NPC's, grander scale, better graphics etc.
If you know me on these forums, you'll know that I'm usually one of those who prefers a locked 30fps with more bells and whistles etc, over 60fps, in most genres besides stuff like fighters, sim racers, twitch shooters etc. I've been consistent in that opinion, and was actually very disappointed when ND first announced UC4 might be 60fps (I made many posts complaining about this decision). I felt and said exactly the same for Halo 5, which imo is not the kind of shooter that needs or has ever needed 60fps, but is the kind of shooter that would greater benefit from a beautiful presentation, and massive sandboxy level design, physics, scale etc. That's not to say Halo 5 might not still feature these things, but obviously at 30fps they could have pushed more. I won't know how sandboxy Halo 5 is till I complete it.
That said, I'm not too fussed either way. I really enjoyed Halo 4, even though it was more linear than past games in the franchise, and even though many disliked it. I also very much enjoyed the Halo's before it (the original still being my favourite, and in my all time top 10). In all honesty it doesn't matter what the frame rate it is, or what resolution etc, so long as it plays well, and looks decent (which it looks like it does). Those are ultimately the fundamentals, everything else is just preferences, being particular and/or demanding.
