Interesting to know there's a bus enthusiast forum here! I've been interested in buses since I was very young (although I don't know much about them, since I was less than 5 years old). Used to badger my father to take me for a ride on one of the loop services everyday.
So, I thought I was the only one with this interest until my encounter with this bus handbook. Then when the Internet arrived, I realised there were more bus enthusiasts than I thought! But honestly, I don't really know much about the technical aspects of the buses...
I think generally, the buses are fine, although indeed there are many which are less than well-maintained. There is one type of bendy bus in SMRT buses which has a severe lack of handgrips. I think there are less than 15 of them, which is very little for a bendy bus! And lately SMRT seem to have extended the length of the handgrips, probably to make them more accessible. Quite logical, since I thought SMRT buses have usually high handgrips. But the thing is, the added length makes the handgrips a less stable object to grasp, which kind of defeats its original purpose somewhat.
And, some buses have a ridiculously small number of "Bus Stopping" buttons on the frame of the windows. It isn't terribly inconvenient, but it can be quite annoying when you're half-expecting a button there. It used to be the case for only the Volvo MK4s (I'm referring to those SBS27xx ones, with Duple Metsec bodywork, and with the pink[now mostly converted to yellow] seats); now it has spread to the refurbished buses too. Why do such silly ideas get implemented? Mostly in place of these buttons are those implements used to break window in case of emergencies.
Leg-room seems to be a problem for some people on certain buses; and on some buses the seat height is also quite low. And on some buses the seats have legroom and seat height problems. In fact, I had this very problem just yesterday, while riding 8N. Mind you, I'm not tall. In fact, I'm only average (1.7m). That bus is an old one so I guess the average height wasn't so high when the bus was first released.
Well, I've seen Malaysian public buses which looked like tour buses; high backrests with blinds for the windows some more.