Sweden had more of everything than her neighbours but there were some glaring issues in the defence structure.
The air force was there, but tiny. Would have been overwhelmed pretty quickly if the Germans had put their backs to it. The fact that Sweden is the home of the 40mm Bofors might alleviate this issue a tiny bit at least.
Sweden got armour going very late, tank production didn't really start until 1939. When Norway got invaded Sweden was in possession of whopping 38 tanks. However, by the end of the war this number was over 800.
Strv m/42 was the main tank used and I'd put it as slightly less competent than a Sherman for comparison, roughly Panzer III levels.
Sweden had a lack of fully automatic weapons and bought anything it could get its hands on, from Finnish Suomis to American Brownings. Lots of lots of nationally produced 6,5 mausers though.
One of the big pluses that is rarely ever considered is the navy. Sweden had a sizable and fairly competent navy for a nation of her size, relying primarily on the
Sverige-class coastal defence ships who were modernised in the interwar period. Each of them carried 4x283 mm heavy Bofors guns and would have made the same style over overtaking as in Oslo pretty much impossible. Depending on how willing the Brits would have been to send aid an invasion over sea in 1940 would perhaps been an impossibility.
One can speculate that this is one of the reasons why Sweden was left out of the invasion plan. Consider the pounding the Royal Navy gave the Kriegsmarine in this phase of the war, imagine if they had been aided by reasonably competent local navy on top of it all.
Manpower was fairly good I'd say, usually way better than the current media gives the army credit for, even if their equipment obviously could have been better early in the war. 100 000 were already standing ready when the first German soldiers entered Denmark.
Prime Minister Per Albin Hansson made a famous speech,
"Our readiness is good", and it is generally considered to be a bit of a propaganda piece today. However, I think there may be some misinterpretation going regarding his meaning. First of all he held his speech in 1939, and I don't think many at this time thought the war would actually spread all the way to Scandinavia. Instead I believe he had primarily the civil defence in mind, such as availability of food and fuel. During WWI Sweden was pretty much close to starvation constantly, while in WWII the country had actually become self sufficient.
Defensive lines were built primarily
during the war. Some fortifications already existed in Scania and they were strengthened. Defensive lines were built around Stockholm (The Sausage line. Don't ask me why). Lots of defences were built along the Norwegian border, primarily in Värmland county, as it was expected that this would have been the primary battlefield in case the Germans decided to invade. The fortress of
Boden was strengthened too.
Sweden's main strengths was it's industry, which meant that during the first few years that Sweden was left alone it could arm itself into a state that would have made invasion simply not worth the trouble.