Will it get better?

It depends what you mean. The later episodes don't have a sharp change in style or anything like that so if you just don't like the way the early ones were done then maybe it's not for you. For example it's not going to become fast paced at any point (except very slightly when they spring the trap to catch the mole).

You say it's been a 'real effort' to watch. It certainly demands concentration, which is something its fans like. That said, I think a lot of people find it quite confusing on the first watch if they haven't read the book, and enjoy it more on second viewing. It's not easy following the story of how a mole named Gerald learns how to make witchcraft using chickenfeed and runs away to the circus.

"Better" is a matter of opinion. This is one of the best espionage thrillers ever produced, IMO.
But I have to be in the right frame of mind to watch it. Like the other poster said, it requires concentration and attention to detail to really understand what's happening. And it has a real "slice of life" tone to it. A lot of today's viewers aren't used to this. As far as more recent productions, I would almost compare it to something like "Mad Men."

Oddly enough, it took me around three episodes to get into the show also (although I was hooked by the fourth episode)
But having not read the book, I did find some of the spy 'jargon' a bit baffling at first (so I can see why the 'stately' pace and 'dialogue' mightn't be for everyone)

Bought 'Smiley's People' today (gonna binge watch it tomorrow)