Both spells say that one can avoid entrapment with a reflex save. Forcecage is explicit so that if it cast around you, you are entitled a reflex save.
However, wall of stone is still ambigious. Let's say for example, the caster creates a wall 25 ft. x 25 ft. x 5 ft. Is every person inside that area allowed a reflex save? Where do they end up if they succeed?
What if a caster just creates a wall to separate the group? Are reflex saves allowed to choose which side of the wall you're on?
What if a caster creates a wall the surrounds someone except for a 5 ft. opening? Are they allowed a saving throw?
E.g.
XXXXX
X......X
X..O..X
X......X
X......X
XX...XX
X = wall, O = character.
Well, many of the questions are still unanswered, but this begs the questions, how is forcecage better than wall of stone anymore? If I can leave an arbitrary hole in the wall of stone that the captives could conceivably escape from, then I effectively have a no save spell.
The only advantage forcecage has over wall of stone is that you need a disintegrate to get out of it, but then again you can save your way out of a forcecage now. The being said, I don't think a two spell level difference is remotely fair anymore, unless the text of wall of stone is changed.
Honestly, I fail to see why forcecage was changed at all. In epic level play, it's one of the only options a caster has to disable opponents, and even then it doesn't do any harm to the subject(s).