overall it is fun, however wasting goo on shooting pistol is meaningless; charge tossing deal way more damage and hit enemy way faster without spending goo.
Also, tommy gun and shot gun are very poor to use, they basically drain out your goo if you aren't aiming well; won't call them actually "upgrade" since they get me in trouble all the time.
if you want to beat this game fast then you should totally ignore your pistol I think.