Greven's Rating system:
5.0: First pick no matter what. I will always play this card.
4.5: Splashable and first pick worthy.
4.0: First pick pack 1.
3.5: Early pick though not always a first pick.
3.0: Solid early/mid pick.
2.5: Solid pick in color.
2.0: Should generally make the deck if in this color.
1.5: Decent filler.
1.0: 23rd card if you have to.
0.5: This card will sometimes be sideboarded in.
0.0: I will never put this card into my deck (main deck or after sideboarding).This card is just very solid - and very nearly free. I would probably play 3-4 in any 3+ color or landfall deck.
I did screw the up at the pre-release by revealing late game when the last thing I wanted was a basic land.
I believe it is strictly correct to look at the top 5 cards (unless you have already scryed or something and are sure you want what is there ), even if you don't want a land, because the information is valuable. It's not *very* valuable however, such that you might get demoralized by seeing a card you want get bottomed.
(If you are not following, the reason the info is valuable is that you'd rather playing knowing you will never draw an out than play having it on the bottom not knowing...). I guess if you have 5 or 6 Fertile Thickets then late in the game you could probably totally restack your deck!