Apple cinnamon is really tasty, raspberry is pretty good, "tropical" felt like there was a party in my mouth where everyone had dysentery (not a good review, to clarify.)

For whatever reason, the regular "fuel bottles" you get at sporting goods stores don't work all that well with the hammer gel. The hammer gel branded flasks had a wider opening than the others that I've found, which was needed for the added thickness of the gel at full strength.