In terms of people management I think Southgate is a nice and good fit and has done a good job.
Tactics are mind boggling, though he deserves some credit for the focus on set pieces.
The five at the back he tried to play has to be the most pointless tactic ever given the good amount of individual quality England has. Now you end the tournament not having beaten any half decent opposition, conceded a goal in every match but one, couldn't defend a 1-0 lead against Columbia.
What the hell is the point in having three centre backs then? Might as well play with two centre halves and field another half decent footballer in attack or midfield and actually try to play instead of passing it back and forward, waiting on set pieces and bottling leads.
The tactics really were crazy. The commentators were treating Southgate like he was Tactical Jesus, but I was really disappointed in them.
You have players like Kane, Sterling, Vardy, etc who like to play off the last defender. So instead, Kane plays as an play-making attacking midfielder, leaving Sterling up-front by himself. Sterling who can't shoot, and really needs to play up-front in as part of a front three. Right. Now there was some logic in using Kane in this way, as he was actually quite good at it, and it meant he couldn't be marked out of the game (he was never in the game). Instead, he was used to bring in Alli and Lingard to score the goals.
The advantages of that are numerous. It's a compact formation that let's you play through the opposition even when they have 10 men behind the ball, and it keeps a fairly solid shape so you should avoid being hit on the counter. And if Sterling, Alli and Lingard were better players, maybe we'd be playing tomorrow. Henderson too, he is the other point of the diamond, and if he was Pirlo then we might looking at our second star.
But it's surely the wrong formation to play when Sterling is a poor finisher, Kane is a fantastic one, and Lingard and Alli can't be relied on to score all the time.
I'd probably have just gone for a front three of Sterling - Kane - Rashford and gone for a 4-5-1/4-3-3. But I don't think that would have won the thing either.