I guess this will be most preferred train as an alternative to bus. At present, Super Luxury buses(APSRTC-Non AC- push back) costs Rs. 820 from Tirupati to Samrlakota whereas DD costs Rs. 770(which is AC-same reclinability). So, las minute pax will always prefer this train compared to buses. If one wants Garuda-like seats, they can go for 3A.