I quite liked the pilot episode, even though it’s basically a worse version of the first half of 28 Days Later. Episode 2 was such a huge vault down in quality, though - the whiplash could break your neck.
S5 definitely is the start of the slow decline (that accelerates like mad in s7-8) but there's moments of greatness throughout. Hardhome (S5E8) alone is worth watching that season, at least, and S6 is arguably a slight step up from 5.
Then he should just say that.
I've been a Tycho defender for a while but it bums me out that "every step of the last 18 years" has led to being just another synthpop revivalist, a decade after the fact.