I had a lot of fun trying out this style of gameplay. HOMM 2 offers an interesting concept of turn based gameplay centered around grabbing resources around the map, while upgrading your heroes cities, powers and raise huge armies to assault your opponents with.

The combat is interesting and challenging enough because you have to take in account every numbers laid out (damage, hitpoints per units, unit sizes, speed etc.). It's a more intricate style of chess (or checkers even) that requires you to think ahead against your opponent's different army setups.

The main campaign is really good in the challenges it brings, without necessarily over stretching the length of gameplay. Although I will warn you, the AI is both very smart and dumb. You WILL need to think carefully in your decision making.

As for the expansions, I can't really say much as I haven't tried them, but I've read that they are hit or miss. I personally had enough with the main campaign alone, so I might just skip them altogether and go straight for HOMM3 instead.

You can grab a copy on GOG for relatively cheap prices (and often goes on sale for less than 5$):
https://www.gog.com/game/heroes_of_might_and_magic_2_gold_edition