Perlman and Ashkenazy can be a fantastic duo - their Beethoven Violin Sonatas are spectacular, with the Kreutzer in particular achieving a level of inspiration that's rarely attained. By comparison, their playing is more earthbound in the Brahms Sonatas. There's nothing wrong with them at all, apart from perhaps over-miking the violin (a fault often found in Perlman's recordings, though happily not in the Beethoven Sonatas with Ashkenazy).
Overall, you're unlikely to be disappointed, but there are better alternatives around in my opinion - Oistrakh/Richter are absolutely fantastic in Nos. 2 & 3, but the latter is pretty hard to find. For complete sets, see Musica Viva's recommendations, to which I would also add Mullova/Anderszewski and Capucon/Angelich.