I have been doing some testing as I - and many others - have observed that stealth is not providing much stealth. Tests were done with 5/5 MOD. For the sake of control, I did not test against human characters even though it is easy enough to watch for perception, and I tested against bad players (primarily <Big Plays>). I made sure the players knew I was there, and when they began looking for me, I slowly creeped toward them to measure the range at which I was spotted.
If the stealth user is of marginally higher level than the opponent, the range of visibility is fine. 2-3 yards, only if in front of the target.
If the stealth user is the same level, the visibility range is inconsistent. Sometimes I can get within 5 yards, other times I am spotted from further. I was charged several times by warriors at the same level as me, indicating they could see me from at least 8 yards away.
If the target is 1-3 levels higher than the stealth user, the functionality of stealth dramatically degrades. At this point, warlocks can dot me from 15 yards+ while stealthed. Mages can poly. I can also be seen while completely adjacent (90 degrees) to the target player. In my opinion, this is the most critical problem with stealth - marginally higher players should not be able to detect stealth so effectively. This is not congruent with the functionality in retail 1.x.
If the target is >5 levels above the stealth user then stealth is ineffective. I also consider this inconsistent with retail 1.x. A level 50 should not be able to see a level 44 from 25 yards away. I tested this against a level 50 paladin yesterday.