I brew matcha and gyokuro at about 140-160F or two parts boiling to one part cold water. Absolutely no more than 2 minutes on the gyokuro.
The trick is to know how much heat you can expose the tea to before you kill it. You want just enough heat to get as much goodness out without destroying the flavor. I tend to err on the side of lower rather than higher temperature as I prefer imperfect tea to ruined tea.
Prepared well, I find both matcha and gyokuro to have a pleasant sweet-bitter taste if of good quality and prepared with care.
Finding quality matcha is a real pain in the US. My latest adventure was Matcha-Koto no Tsuki
. It's actually quite pleasant, bitter in the perfect dimensions and proportions with enough sweetness to carry through to sublime experience. Luckily, it is available 7/10ths of an ounce at a time as it costs almost $500 per pound. That's about $10 per serving and well-worth the experience many times over if you like matcha.
Consider that many premium matchas cost over $700 per pound and come in 30g (1.1 oz) tins--and often don't live up to the price.