I'm up to Mission 6 and have been having a great time, despite some clunkiness and a general lack of refinement.
Ragdolls clip into the environment literally half the time, spazzing out with their best Jacob's Ladder impression. Animation in general is stiff and robotic. Enemy A.I. can be comically poor. Even the X-Ray kills, which are obviously a huge focus, don't always play out correctly - impact sounds play too early, bone shatters nowhere near the point of bullet entry/exit, and characters are frequently oddly framed or disappear completely, leaving just a lone bullet and a bunch of crunchy squishy sounds. On top of all that, the game is buggy, with one in particular that prevents progression.
And yet, I'm having a great time. The moment-to-moment gameplay is fun and satisfying. The levels are not only huge, but are also surprisingly diverse in both setting and layout. Rebellion made good on their claims that this game would be far more open than V2, with impressive freedom in how you approach each scenario. A lot of the levels are genuinely great, and there's not a single one so far that I'm not looking forward to replaying.
Sniper Elite 3 is flawed, sure - seriously flawed, arguably - but man, is it fun.