The rare allied colors cycle has been discussed and reviewed by too many already. They will be good in Standard. Some people call them Tangolands. I call them Suckerlands.
Ally Encampment: add 4 to your Ally deck, done.
Blighted Cataract: nice late game card draw.
Blighted Fen: nice late game sacrifice, although your opponent could have a choice to sacrifice a small critter.
Blighted Gorge: would be fun to use it as a game finisher just because. Seems like one of the weaker lands in this cycle.
Blighted Steppe: life gain usually delays the inevitable. It has a home in the white/black "Friends of Ajani's Pridemate" deck. Seems like one of the weaker lands in this cycle.
Blighted Woodland: very nice indeed. It replaces itself and gives you an additional land. I like it a lot.
Fertile Thicket: careful use required. OK, you dug up a basic land, and you could also end up putting four very good cards for that phase of the game at the bottom of your library. This card could backfire big time.
Looming Spires: a small effect for a tapped land. I am not sure I would use it.
Mortuary Mire: nice effect at common. "Target creature" can be one of your major threats. I like it a lot.
Skyline Cascade: could gain you an extra turn to do something against a big threat. I like this one although not as much as the black one.
Sandstone Bridge: a small effect for a tapped land. I am not sure I would use it.
Shambling Vent: one of the two money rare lands, and the one with the smaller casting cost. I plan to play it unless it becomes ridiculously expensive.
Lumbering Falls: one of the two money rare lands, and the one with the larger casting cost. I plan to play it unless it becomes ridiculously expensive.
Shrine of the Forsaken Gods: its a nice boost in an Eldrazi deck. This set's Eldrazi Temple. Should be very useful.
Sanctum of Ugin: this set's Eye of Ugin. It is not Legendary, and that makes it really really good, but you have to sacrifice it, and Eye of Ugin does not need to be sacrificed.
Spawning Bed: a little heavy for the effect, but in casual that does not matter. Great casual card, must play.