My insight, and how I'll use them. Take this with a grain of salt.
Comparator: 5/5 Good for inventory checking, comparing, and among other things. Time will tell how useful this is to me.
Hopper: 4/5: It's good, but slow as molasses. I like how it can auto extract, the texture is good, and it looks better than the BC hopper IMO (It's blockier..?)
Dropper: 3/5: Useful to someone other than me as I don't like spewed items, and the transposer fills this role without needing a clock. I like how it can push to inventories.
Activator Rail: 1/5: No use for this. Railcraft does it better and Covert's carts costs 5 wooden slabs instead of vanilla's 5 iron. I'm not going to waste my iron that quickly.
Daylight Sensor: 3/5: Comparable to Redpower's light sensor, but isn't adjustable. Makes up for the fact that it outputs strength signals. Good for a clock.
Trapped Chest: 0/5: Completely useless, for the sole fact that it has a different texture. If it used the chest.png, 5/5.
Weighed Pressure Plate: 2/5: As I don't use vanilla sorting systems I've got no use for this, but I can see a good use for other people. I'm against having items spilled on the ground, though.
Block of Redstone: 4/5: About damn time. It looks pretty cool too. Coal now?
Craftable Nether Brick: 4/5: More aesthetic options are always good for everyone. Never a downside.
Nether Quartz: 4/5: More ores to mine is always better, more nether content? Even better. The texture is good, as well.
Quartz Aesthetics: 5/5: Take my money, holy shit. I won't even be using quartz blocks but I love the look.
Nameable Mobs: 0/5: I can see a great mapmaker use, but as a normal player? Useless.
Placeable snow layers: 3/5: I've really got no use for this, but I like the differing layers. Looks good.
Dispenser/Dropper facing direction: 5/5: I love how the two can now face upwards and downwards. A+. Dispenser floor aiming up, loaded with water buckets. Instant river.
The new middle click drag and right click drag crafting funcitonality: 5/5: Where have you been my life? It evenly splits stacks! HOLY SHIT
Spawner carts: 0/5: Mapmaker use ONLY. No use for the normal player, at all.
Hopper carts: 3/5: Good concept, good functionality, but I won't be using them as I don't like spilled items.
New smooth lighting: 2/5: It doesn't look any different to my eyes, and causes EXTREME LAG for me. I can normally rack up a 150+ FPS without vsync, but it drops to a cool 40 with SL on. Optifine to the rescue, again.
Texture splicing: 5/5: I'm a texture artist; I love making textures. Now that animated textures are a thing, it's super organized, and I love it x 10.
Bonemeal mechanics: 3/5: I'm torn on this one. I love things being hard but damn is this iffy.