Given its significance in the career of the great comic W.C. Fields, "Pool Sharks" would certainly be worth seeing for its historical interest alone. In itself, it's probably just an average feature for its time and genre, and it doesn't give Fields the chance to shows his greatest strengths, but it is fun to see him in such an early screen appearance.
You can see the strong influence of Chaplin and Keystone, as the plot and all the characters are patterned after those styles. Fields plays one of two rivals for the hands of a girl, and his character gets involved in the kind of manic slapstick that characterized a great many short comedies in the mid-1910s. Nothing wrong with that at all, and while "Pool Sharks" in itself would not stand out, it probably would not have left too many of its original viewers disappointed, either.
Besides the slapstick, there are some visual effects with the pool table, and while the special effects technique is rudimentary, it's amusing enough.
For the most part, Fields himself just has to keep up with the madcap pace, and cannot do some of the things that he did best, yet you can see his talent when he has the chance to show it.
