It is probably not legal. But sites like oosai.com have the songs from the movie in streaming format.
I don't expect Rahman's music to be catchy in the first listening. You hear it again and again and start liking it. Of the six songs (seven if you count the two versions of 'Sahara Pookkal Poothatho'), just two stay in memory. 'Sahara Pookkal Poothatho' by Udit Narayan, Chinmayee and Vijay Yesudoss, Gomathi Sree is probably the best of the lot. The song is not great, but is at least good enough that the tune stays in memory after the song is over. 'Vaaji Vaaji...' by Hariharan and Madhusri is slightly fast paced, catchy and could be a hit. Madhusri's voice reminds me of Lata Mangeshkar's current voice. Nothing more to write about it. The song 'Kaaveri Aarum...' by SPB appears to be the usual Rajini's opening song. My father would comment as - 'தெவச மந்திரம் மாதிரி இருக்கு'.
On hearing the songs, I feel A R Rahman is getting old. When was the last hit from him?
While typing this blog, I heard some of the songs a second time to get the lyrics. Hey.. I like them. Hmmm - Another Rahman's album here.