Problem with traditional MSAA is that it doesn't handle HDR that well.
MSAA resolve to pixel level is done before tone mapping and so it can 'miss' a high contrast areas.
Also if MSAA is resolved before things like deferred shadow, fog or lighting pass it's effect can be completely erased. (IE. Gears of War, Froza5.. etc. (both had 2xMSAA))
Most of these problems can be bypassed by proper custom resolves which is the future of edge AA.
4x SMAA combines 2xMSAA samples with temporal re-projection with edge detection and reconstruction and has very good quality.
TXAA is basically MSAA with resolve done right with very nice temporal aliasing solution which reduces all kinds of flickering aliasing. (It also has tent MSAA resolve which blurs a picture a bit.)
For next I would love to see someone to mix those two methods as the result would be incredible. (edge reconstruction, temporal re-projection with flickering reduction.. etc.)