That probably depends on your audio needs.
XAudio 2 was designed to address some of the limitations of the original DirectSound API, which was designed back in the mid 1990's when ISA soundcards with on-board audio RAM were all the rage and a cutting edge PC was a 66MHz Pentium I. XAudio 2 was designed with a software implementation in mind.
If all you need to do is play back a few sound effects, and you know DirectSound, then it'll probably work just fine.
XAudio 2 does support several useful features that DSound doesn't, though.
Native run-time decompression (ADPCM and wma), digital signal processing (for reverbs, filtering or arbitrary audio processing), submixing, audio graphbuilding and a more transparent 3D implementation. If you think you may want to use those at some point, it's probably worth learning and using XAudio 2. (the compressed sound support alone may be worth the switch).
Big Disclaimer-- I was the primary architect for XAudio 2 back when I was at Microsoft, so may be biased .
There are of course other 3rd party audio API's out there such as FMOD, WWise, Miles, etc, that may be worth looking at.
Final 3 weeks for Earlybird Discount
GameSoundCon 2012, San Francisco.
XAudio2 is perfect,however it just doesn't run,it wants some XAudio2_8.dll.I don't understant WHY it wants the DLL,when it's obviously a Windows 8 dll that hasn't even come out yet,why does my code in Windows7 in a normal DirectX11 application require me to have a DLL that is in Windows 8,how do I get that DLL?No one seems to have info on the issue of missing XAudio2_8.dll.I can't even call it missing,since it's not even supposed to be there,Windows 7 has XAudio2_7.dll.Why my program requires a dll that it shouldn't even know about is beyond me.