It’s not too bloated (I tried to keep “novelty” mods to a minimum) with sort of a loose “science versus magic” theme and a bit more survival than you would normally see on minecraft. There is a few slight configuration tweaks regarding ore generation, temperature effects on armors and a few other things. Also the presence of the “sync” mod allow you to clone yourself to cheat death, even in hardcore mode. While this potentially makes the game much easier, it doesn’t come for free and survival in the nether is much more difficult.
The science side is focused around Universal electricity compatible mods while the magic side is supported by ArsMagica2, Thaumcraft4 and Mystcraft.
If you play minecraft and have the Technic launcher, why don’t you give it a try?