Whenever I have watched him play for Wales, I've been impressed by him. When he plays for Arsenal (at least recently), I have been far less impressed, but that could have something to do with the general dysfunction surrounding Arsenal of the past few years. He seems to be performing better even for Arsenal this year, now that Wenger is gone. Has 6 assists already. We could use a player who can provide assists and final balls to our attackers out of the midfield.
You're exactly right imo about it being a good signing in winter, but perhaps not so great in summer. People expecting a big CM signing of a top player mid-season are always going to be disappointed, the market just isn't there for desirable players and prices are silly as teams are extremely reluctant to let their best players go for obvious reasons, and the signings often don't work, due to the trouble integrating top players into a team mid-season. So a low price move for a player with good upside like Ramsey seems a good move to me.
However, I'm not sure why Arsenal would sell him to us mid-season, while locked in a top 4 battle for a CL spot next year. Especially for peanuts.