I've had a chance to really mull over and test Luigi's changes. Here's my analysis:
D-Tilt: The tripping is good (but at a 0.35 rating still), and the edgeguard from the ledge is good, but we lose it as a 50/50 from jab. Well, we still have it, but it doesn't lead into much anymore. People are sent too far away to follow up. Who was using it for edgeguards, anyway? We have several tools better at that then D-Tilt will ever be.
Fireball: The big one. Jab-locking missed techs wasn't a huge deal, since we have a few moves that extend it and we can Up-B after the first, anyway. The 3 frames increase the deadzone where we can't get grab off of a fireball by half a Luigi. Considering that we're either in their face or just close enough to get to the sweetspot zone for fireball, we now need get in slightly more overall to get a grab off of it. It does hurt our approach a bit.
Fair: It combos... The same, save for like 10 matchups at specific ranges. It does let us get an extra up-air at a specific range in all matchups, so that's nice. It REALLY hurts air footsies, though. Now, we either have to Bair to get a decent reward (and stale it, so D-Throw > Bair is less potent), or we go with Fair and lose 1/9 of the damage each session. It MAY lead to a forced grab due to universal landing lag that characters have (2-3 frames of animation), but that will take a lot more testing.
U-Throw: D-Throw > Nair kills well before this kills even still, so I don't see the point to the buff.
Up-B: Ya... It kills 10% earlier, but how often are you getting it? How often do people let you hard-punish with it? It's a definite plus, but one that won't play into our game every game or set.
Overall, he loses a grab option, has a nerfed approach option, worse footsies in the air, a better, but irrelevant, up throw, and a better up-B.
Overall, I think he has the same power level as before. It's just distributed differently.