The town of Imotski does not have much of interest to offer in my opinion. A small place with a population of just 5,000 inhabitants that lies sleepily in the heat of the summer sun, Imotksi has neither sea nor mountains in which to go hiking close by. Inevitably, therefore, a visit here can get a little boring. I would not necessarily recommend coming here.
The most interesting thing the town has to offer are the two lakes located on its outskirts: the Blue Lake and the Red Lake. Both lie at the bottom of dramatic crevasses and offer quite an impressive spectacle. There are various walks you can do around them, and it is also possible to go bathing too. The Blue Lake has a medieval fortress standing overlooking it, providing a good opportunity to take some impressive photos.
And finally, if you do decide to stop and visit Imotski during your travels around Croatia, don't forget to sample the local nut-and-almond-based sweet ravioli, which is the town's speciality!