1. Go's over-fitting to Google's development style, especially the over-reliance on dependencies as source-code.
2. Go's lack of hackability that might bite you down the line when you need something that Go really can't provide. Go's only hack-hook is source-code manipulation (which brings us back to point #1), and at this early a stage we already see too many tools going down that ugly road.
Go is probably the least hackable mainstream language I've encountered. In C/C++ you can always poke around the implementation details when there's no other choice; with Rust there's unsafe; with Java (and other JVM languages) there's full bytecode control; with scripting languages there's metaprogramming. All those "backdoors" should, of course, be used sparingly if not rarely, and then are best done by experts and hidden from sight, but they're always there for when you need them -- and you invariably do for that last 1%.
With Go -- there's absolutely nothing. You can't even drop down to C to muck about because you'll mess up the delicate runtime. So Go is indeed a descendant of C, Java and Python, but neglects to provide the hackable escape hatches from the plain language semantics all of them do.
Those two things scare me (not that I'd give up on deep monitoring or polyglotism otherwise, but still) because not only are they risky, they're exactly the kind of thing that people don't notice when the project is young. I feel like there's a very important lesson here that seriously bit people in the ass that Go failed to learn (well, that and no support for immutability of any kind).