After I have played 1.7 for a long time,I realized that terrain is kinda terrible.They seems didn't improve anything at all.They only do is adding more biome varient and some new biome into it.Other than that I don't see anything which nice about the current terrain.
The top reason why the terrain is still bad even they have update it is they rely on technical biome too much.I do feel technical biome has ruined every nice part of terrain because every mountain varient can only generate in technical biome such as Ice Mountain,Taiga Mountain and Forest Hill.If you have played on Beta,every hill can generate extreme hill like overhang and it is possible.This is no longer happen after Beta 1.8,I thought 1.7 Mojang would not using technical biome but I'm wrong Mojang still rely on technical biome.

Alos,the temperature system is TOO STRICT.I playing on a survival server and traveling same direction for 1 hour straight.After 8000 blocks,I only found 1 savanna rest of it is forest,plain,snowless taiga and extreme hill.

Now I will review every biome one by one .

Ocean
Good's
-Making world of Minecraft more vast
-You can play survival island in it
Bad's
-The second name is called big lake because their size is greatly reduced
-1.7 ocean floor is replaced by gravel,this is totally stupid.Gravel doesn't have any use.The old ocean floor has more use because you can use dirt to expand your island,sand for glass and clay for building
-Transition between ocean and beach biome is still worst

Deep ocean
Good's
-Slightly more realism
Bad's
-Same with Ocean biome

Plains
Good's
-Horse seems spawn more frequent than 1.6
Bad's
-Same with 1.6,plain is still full of hill.

Sunflower plains
Good's
-You can find some sunflower there
Bad's
-Waste of biome id.Why can't sunflower spawn like other flower?

Forest
Good's
-You can found wolf
Bad's
-Why they removed big tree in this biome?

Flower Forest
Good's
-Flowery
Bad's
-Why some flower must be exclusive to this biome?

Swampland
Good's
-Comparing to plains,this biome is more suitable to build because it is more flat.
Bad's
-Some flower is exclusive in this biome
-Why this biome have 2 biome color,it is very ugly to see 2 biome color in the same biome.

Swampland M
Same with swampland

River
Bad's
-It has their own biome colour,making some colour with greener grass(jungle) look very ugly when river cut through it
-Cut through terrain
-Passive mob can't spawn in river biome
-It is very ugly to see a river biome cut through desert and mesa

Mushroom Island
Good's
-Hostile mob not spawning in this biome.
-If you place grass in this biome,the grass colour is very beautiful.
Bad's
-Hard to find cave because Mycelium covered it.

Beach,cold beach
Bad's
-Looks extremely ugly comparing to real life and Notch's beach.

Jungle
Good's
-You can found some cute ocelots here.
-Melon generate in it.
-Cocoa spawn there
-Nice biome colour

Birch Forest
Good's
-For anyone like to use birch wood,this is best biome for them

Roofed Forest
Good's
-Huge mushroom spawn in this biome
-The Dark Oak Tree provide many wood and easy to chop down.

Desert
Good's
-Very well generated,no ponds(except in Desert M) and hill is quite awesome

Savanna
Good's
-Tree generate in this biome
-Village can be found in this biome
Bad's
Basicly this biome is rip off of plain biome except for the savanna m which is very awesome.

Mesa
Good's
-Colourmatic
-Good for people need lot of dyed clay.
Bad's
-The red sand is quite kinda waste of block id and very hurt my eye.

Extreme Hill
Good's
-Some nice overhand can generate in this biome
Bad's
-This is the only biome which you can find real mountain.The hill biome can't generate epic overhang.

Taiga Snowless
Good's
-Return of snowless taiga on Beta 1.8
Bad's
Any Taiga generated in 1.6 will facing global warming in 1.7

Mega Taiga
Good's
-Very well generated

Ice Plains
Good's
-For anyone love to survive in snowy place with little tree,this is a very good biome.
Bad's
-This biome's size is very large comparing to other biome,it is quite imbalance.

Ice Spike Plains
Good's
-For anyone like to look at cool structure,this is a very good biome.
Bad's
-If you living in this biome for a long time,you will found these ice spike is very waste of space and boring.

Cold Taiga
Good's
-Snowy place

Oh ya,one more thing which I found extremely annoying and didn't get fixed ever since Beta 1.2,water lake is too freakin' common causing holes everywhere.I felt Minecraft's terrain is completely destoryed because of common water lake.The lakeless desert is very neat because there is no hole everywhere.

Thanks for reading this.Sorry for my bad English,English is not my primary English.