Here and Now isn't quite as bad in New Vegas than it was in Fallout 3, but it's still a lousy perk because leveling up in both games is all too easy. And when you gain that extra level with Here and Now, you don't get to pick a perk with that new level. So you've wasted two perk slots; one on Here and Now, plus the one you would have gained if you had leveled normally, at least in Fallout 3. Since you wouldn't get a perk in New Vegas with the next level anyway, you're not losing anything by taking it, which is why it doesn't svck as bad.
As far as the rest of the ones you mention, they're more situational or preferred build oriented. Some characters might find them very useful while others will have no use for them at all. I'd say every one of then, though, is far better than Here and Now.
Retention - if you use magazines to buff your skills a lot, the extra time the buff lasts could be very useful. It would be more useful early to mid game than it would be late game though, since by then your skills without buffs are going to be higher. I usually don't take it myself.
Bloody Mess - personal preference. Some people like seeing blood and guts flying everywhere, some find it annoying. The 5% boost to damage is okay though. As far as I'm concerned, I get tired of the gibbage quickly.
Math Wrath - someone who uses VATS a lot would find this one very useful, especially combined with other perks that improve action point amounts and regeneration, and perks that increase VATS hit chances. If you don't use VATS much, then it probably isn't worth taking. I don't use VATS much, so I don't take it.
Hand Loader - very, very useful for a Guns character who uses the custom ammunition recipes at the Reloading Bench a lot, which most Guns oriented characters probably will. All of my Guns characters take this one.
Friend of the Night - a character who wants night vision without having to bother with buying or scrounging Cateye or Ghost Sight might find this one useful. Me, I usually try not to be out at night if I can help it.