I have used bow and stern thrusters a lot on commercial / coast guard vessels.
On commercial ships they are essential as otherwise many port authorities/pilots would oblige you to take a tug for berthing with all the expense that incurs. Also, for DP (dynamic positioning) they are essential.
On pleasure boats though I go along with SpawnyWhippet, in fact, I would go further and claim that such devices promote poor seamanship or, at the very least, a lackadaisical approach to boat-handling
See also an earlier post of mine here.
Aye // Stephen