Second, a list of (hopefully helpful) criticisms:
(1) Re: Intro video. Way too long. Don't need to see the face of the founder. How can you use an ordinary hot water heater and discuss water temperature? At least pretend to stick in a thermometer -- or, better, use a Zojirushi or equivalent.
(2) Should probably have preset times/temperatures for different tea types that can be edited, to facilitate data entry (maybe you do, but I didn't quite pick up on this in the video).
(3) Perhaps I'm the only one, but I find data entry (including tasting notes) to be a major pain on an iPhone. I used to keep my cheese tasting notes on mine but gave up since I hated doing it that way. I suspect that people will not continue using the app if they find the most useful features require significant data entry.
(4) Key and very useful feature(brewing timer) is already included as part of the free Teavana app. Also the Teavana app has nice music while you brew.
(5) Killer feature would be tea ratings and the ability to share. You might also want to rate them based on vendor. Or, potentially very profitably, allow direct buying with the purchase automatically imported into the app. That's what my app was structured around. To get a more long-term hold you probably need to "go social" at some point.
(6) Hardcore tea snobs (this term should probably include myself) frequently brew tea in different pots, vessels. You might consider including this -- and obviously you would use different amounts of tea depending on the vessel.
Best of luck! Definitely a huge improvement over what else is out there -- and personally hope it makes it into an app not tied to iOS.
About me: I got into tea while working and studying in China and Japan and once built a (skeletal) Rails app for rating tea that I never released. I still think this could be profitable but am now instead n grad school reading about Tea -- and have also identified several favorite vendors such that I feel that I have everything I need at the moment.