1.5 + mods in a nutshell:
Eloraam will update in 1.7, + 200 bugs and 2-3 new features, then disappear again till like 1.9
Thaumcraft will change everything again, also in 1.6 and 1.7, lets see what thaumcraft 10 has to bring us in the future!
IC2 will have the same exact stuff, nothing new as always.
Gregtech will make you use nether stars to chop down trees (1 nether star per log)
Instability of mystcraft now might give you viruses on your pc, and no age may be usable.
Stell in railcraft now will take 1 minecraft day to make, and high speed rails will blow up stronger than never before
200 new species of bees
Solar panels now require dragon eggs to make because they are so op
Buildcraft will invent something weird and new, sorta like lasers of the assembly table
Xycoridite will now be as useful as dirt, really good for growing stuff on them, besides storing lava in wooden tanks like is nobody's business, oh, and powering footbals with lasers, thats for sure!
Everything will be laggy as hell, as always
Voxelmap will show you mushroom islands near by, and ever ore in a cave if you choose, or chests, sorta like nodus
You will have molten of every item in game and be able to put it in a frame of whatever to make a new TE item
EE will let you exchange cobble for nether stars
Extrabiomes will have 200 more useless biomes so you wont be able to find that extreme hills for emeralds for your tinker table
Modular powersuits now will cook your food, walk for you and kill for you
Portalgun will now require you to be at the farlands, have 200 spawners near by and 29 activated beacons to make 1 gun
Reliquarry will now have 200+ guns like battlefield
(This is a joke, as people might not get it)