Irctc app and website is nice it has good interface it gives us every way to book tickets and tatkal tickets too but the main problem is at the exact time the server seems too busy.
Recently I used it to book 2 tatkal tickets from Patna to New Delhi at 11 am I was ready with everything like debit card internet everything the clock strikes 11 am and I logged in and typed the journey details it gives the train list and I selected one of the train from the list, I waited to open of it and it shows 180 seats available I selected and filled up the passenger details and at that time server takes too much time to book it and when it opened it shows 10 waiting so I didnt go to Delhi at that time after that I have to give it to an agent to book my tickets then after I went.