The bus can be hot, but I actually enjoy it. It's slower pace allow you to get a glimpse of Aruba and it's people. Our first trip, we missed the Divi stop when coming back from downtown, so we just stayed on and had a mini tour of the high-rise area. The bus driver was kind enough to alert us as we approached the Divi stop.
We have taken the bus a number of times from the Divi to the high rise area. It's great - cheap and relatively quick, however we are not in a hurry so we really don't notice. We have even taken the minivans I guess operated by individual citizens which can be really interesting. It's mostly all locals. The first time we weren't sure, but it worked out well and we have taken them a few times.
I was in Aruba this past week and was going to take the bus to town. As I was waiting at the bus stop a van pulled up which said BUS on the side and we took that for the same price as the bus from the Hyatt. We did stop along the way and pick up others but it was more comfortable than a large bus. We did the same going back to the high rise area.