I first saw this pitcher when I was looking for the same thing but with an ice core instead of the infusion core (which just happens to be made by the same company). I thought it was a great concept; and since I'm always looking for ways to add more water to my diet (without having to drink plain old ordinary water), I decided to give it a try. I was immediately hooked!
Here are a couple of things that I've observed:
Distilled water works best.
Depending upon what type of fruit you use in the core, it can take up to two days (or more) to get a really good infusion. Citrus fruits tend to take longer to infuse than berries.
It's a good idea to add water to it each time you pour yourself a glass. Two reasons: first, the newly added water will mix with the already-infused water and will take less time to become flavored. If you wait until the pitcher's mostly empty, it'll take a while to get a good infusion. Second, a smaller amount of "new" water will take less time to chill than if you were to add a whole bunch of new water.
And here's a hint: If you make your own lemonade (from scratch), try using orange-infused water to your lemon juice instead of plain, unflavored water. It adds a wonderful touch of "something" that you can't put your finger on (you KNOW there's something else in the lemonade, but you just can't figure out WHAT).
And, lastly, a suggestion: don't wait for berries to come into season! Just use frozen ones (strawberries, raspberries, mixed berries, etc.) Because they've been frozen, they tend to infuse better than fresh ones. I recently used half a package of frozen raspberries. As they thawed they immediately began to turn the water red and by the time they were completely thawed, I had a lovely shade of red raspberry water. Being a "sweetaholic", I add a packet of stevia (AKA Truvia, but I prefer the Whole Foods brand of stevia) to my raspberry water and it tastes like a healthier version of raspberry Kool-Aid!