Like nearby Kamphaeng Phet, but smaller, Tak is a town which receives very few tourists, the majority of which are simply passing through en-route to somewhere else.
Tak isn't a bad place to spend a day if you're passing through -- it's a distinctly rural town, running in principal along the Ping river via four parallel roads which are interconnected by a warren of small sois. It's a good place to visit if you're looking to observe a normal Thai town which hasn't earned its keep from tourism. The reality though, is that there is very little to do here besides put your head down for the night, grab some local food and supplies, or simply people watch.
The people in Tak are very welcoming and although you won't necessarily find many English speakers you may well find yourself welcomed to join local people for food or drinks, such is the warmth of the culture.
The wooden suspension bridge is the only real highlight of Tak, which is able to take foot passengers or motorbikes, but not cars. By night a small but capable night market sets up on the road adjacent to the wooden bridge, probably your best bet for a cheap and tasty local dinner.
When you arrive in Tak, drop by the TAT office on Jodvitheetong Rd, just a few hundred metres from the bus station. They can stock you up on decent maps of the area as well as more detailed information on nearby sites and attractions.
The police station can be found on Tessaban 1 Rd, and the post office is just around the corner from there.
All major Thai banks (each with ATM facilities) have a branch office in Tak -- many on Mahaadthat Bumroong Rd.
The town is dotted with internet cafes and coffee shops which provide minor entertainment to pass the time. Travel around town is best done by foot, though the less energetic can easily summon the aid of a tuk-tuk or motorbike taxi.
Tak's main hospital, the aptly named Tak Hospital, is on Phahol Yothin Rd.