The terminal has certainly seen better days and could use a bit of makeover. The baggage claim areas are filthy, extremely unacceptable for an international destination long visited by millions per annum. On the plus side however, it only takes a couple of minutes to get to the gates, and is well served by most of the world's airlines, although it certainly is a pity to learn that very few airlines have actually flown there.
It is not customs that is slow here, it is Visa On Arrival and immigration.
Airport is way better than CGK
Visa on arrival takes a long time. So have indonesian visa ready before you land there.
My rating is for domestic terminal. The domestic terminal is way too small and unacttractive. International terminal is another story, it's quite good.