I've heard a billion times from a trillion people that 4th edition is just good for beginners, and not actually better than 3.5.
*shrugs*
It's a lot more streamlined. One or two things I've noticed:
There's much less unnecessary dice rolling, for example: no more reflex/fort/will save rolls, they work like AC now, so the attack roll just has to beat the reflex/fort/will to hit.
Skills are a lot more simplified. There's fewer of them, and they all increase at a constant rate of 1 every 2 levels.
The DM rolls basically everything in a monster's turn, as mentioned previously there's no saving throws that the players need to roll. I hated this at first, but it makes things run much faster.
No more grappling. Thank god.
No more (at least not that I can see) resistance against wooden weapons, etc. Thank god. I think maybe silvered weapons is the exception to this (werewolves, etc).
Armor is so much simpler. There's basically 6 types of armor total, and then just variations and magical variations of them.
The magic system uses the same system as all the other classes. Unlike before where if you've never played a magic caster, you would need to take an entire session to learn.
No more animal companions or familiars. No more waiting a year and a day for a new one.
Races are actually more varied than "humans of different heights".
Magic weapons are actually useful now, and if the DM does things properly then basically everyone should have one by level 2.
Level 1 people don't have a dodgy 7 hp anymore.
The powers system rocks, especially if you make little power cards (with the stats on them) that you can flip over when you use them. The power system is actually where the majority of character variety and strategy comes into play.
Feats are actually useful. No more +2 knowledge (children) and stuff.
Non-combat encounters actually have a system now, and are a lot of fun.
...Yeah, bored now, but that's a few changes they've made. Some are good, some aren't.