Jade mountain is definitely the place to go if you are reminiscing about Taiwanese bubble tea.
They serve the most authentic (in Madison) bubble tea with a variety of flavors and styles. Also featuring a special type of tea: Taiwan Red, it's quite a good alternative if you are looking for something more subtle and less caffeinated than the regular black tea.
Other than bubble tea, they also serve potstickers and ramen (not Japanese style, just FYI) with fish tofu! One new thing that is a must try: their butter mix thick cut toast. Thick cut toast is a very common snack they have in TW, usually served with various kinds of spreadings. Great snack to go with your bubble tea!
They also have a number of chairs+tables with outlets nearby. Plenty of people take an advantage of doing their work there.