I have two, a Snap-On TQFR-series for bigger stuff and a cheapie Craftsman twist-handle clicker-type for the small stuff. Do I use them much? No. I'd use them where they matter, since I have the option... clamping a stem to a carbon steer tube, sure. Clamping a carbon bar into a stem, sure. But I'm not going to fuss with torqueing my rear derailleur to the frame's rear-derailleur hanger at precisely 70-85 inch-pounds If you're a newbie and don't know how stuff goes together, by all means do follow the instructions, and torque your rear derailleur to your frame with your torque wrench, etc.

When fastening stuff that has multiple clamping bolts, such as a four-bolt faceplate on a stem or a two-bolt stem clamp to the steer tube, do try to do it evenly in rotation, stagewise, don't just crank the bolts to precisely 120 in-lbs. one at a time with your torque wrench and call it done. Also, lube the threads and other contact surfaces on stuff appropriately, so you're not pouring torque into overcoming the friction of bare metal-to-metal contact.

Park Tool has a small-sized beam torque wrench for little fasteners if you want a small one. http://www.performancebike.com/shop/....cfm?SKU=11387