If you enjoyed the first Kingdom Rush - this is more of the same except better. Heroes can now keep the levels they gain throughout the game and have more abilities. It has a ton of interesting enemies with unique abilities and brand new high level towers and strategies. This is easily one of the best tower defense games I've ever played. There are some caveats compared to the mobile version though. First it's missing two mini-campaigns (Shadowmoon and Rising Tide). Half the heroes are missing (has coming soon in place of their portraits). No Endless Mode. The devs have stated that those features will be added in future patches. Still, even without those features this game is worth the price of admission.
If you liked the previous games you will like this one. If you didn't this will not change that. The pros and cons are pretty much the same as previous titles except as noted below: Pros: You have a central hub you can teleport to to recruit most evil units (Demons, Undead, Orcs). There is a lot less backtracking to replenish your units as long as you stick with evil ones. A ton of new units with new abilities. Many of them are completely new and not reskinned versions of old units. Cons: No leveling system for units like in Warriors of the North. Some non-evil units you might have trouble recruiting with gold. Can be mitigated with some spells and abilities like sacrifice. Only one boss battle (could be a pro if you did not like the boss battles). Overall: I heartily recommend this game.