The Xs20 is a really good entry level/intermediate cymbal pack.  Make no mistake, they are for beginners, but are waaaay better than most of the entry level cymbals for only a slight price increase.  Like most situations, it is probably better to dish out the extra cash rather than settle for less and regret it.  The Zildjian Zht's are comparable to the Xs20's, but don't come close to comparing in value.  The Zildjian pack is a lot brighter and more coated sounding (ok for certain types of music that require cutting), but the Sabians tend to be a lot more versatile.  These are even acceptable to gig with, and I often find professional drummers using these when they don't want to lug around their expensive stuff. 

The hihats are great for this level.  They have good chick, wash, and stick definition.  They are not particularly subtle or mellow, but no cymbals are for this price.  They aren't overly bright, which is a relief.  The crashes are excellent, probably the best part of the pack.  They gave a good balance, strong attack, and smooth decay.  The ride is ok, probably the least versatile cymbal here because it sounds pretty raw.  The bell sounds great however, and it crashes pretty well. 

Like I said earlier, while the Zildjian Zbt's and Sabian B8's are a toss up, the Xs20's beat the Zht's.  They use the same alloy that many more expensive Sabians use, and this is audible right away.  Forget about b8's or b8 pros, these are where you should look for a cymbal pack if looking for value and quality.  Sabian makes great high end cymbals in genreal, but these xs20's prove that they don't forget about the lower end options either.  I am picky about cymbals, and enjoy playing xs20's very much.