A good idea if you plan to travel around a bit but we hired a car and realised that Uber costs are very low (meaning we could avoid the arguments about whose turn it was to drive...). This is ideal if you're more than an easy walk from beaches/bars/restaurants.
I can't say that was my impression when I was there a few weeks ago. Don't get me wrong, it's a fantastic and beautiful country, the people seem really nice, and the food is great but the prices were not far off those in the UK - our currency has plummeted (and it's only getting worse) so any discount is mitigated by that. Turkey is about the only place in "Europe" where this isn't the case.
Unless you go to Dubrovnik which is quite expensive. I just got back from there. Saying that though....its worth it. It's a really beautiful country. Very busy with tourists especially around the old town (with all the GOT enthusiasts) even though schools haven't broken up. It will probably be busier then.
Croatia is really nice but overrun with tourists in the summer for decades. The last few years have got incredibly crowded. You can still find quieter places in the less popular islands, mainland spots.
One of my major gripes about EU beach destinations. Virtually no resorts have heated pools. The ones that do tend to only heat them a couple of degree's at best, so they are still bloody cold. Or worse still pick and choose wether to heat them based on occupancy/how much money they are making at the time. Only really leaves the peak summer months when you can comfortably enjoy the sea/pool. And then you have to contend with the summer school holiday price hikes :/ As a result we just end up going long haul. Just so much easier when you can allow the kids to jump in and out of the pool as they please. Rather then worrying it's too cold for them to go back in after the first dip.