"Never seen the term pay to improve, pay for perks however is a common industry term." Terminology aside, concept is the same. The game is not quite pay to win, but close is also a very true statement. If InnoGames ever takes out the res/pp exchange then the game is fully PtW and in my honest...
Marty Sox, Your about 5 years to late. Game has been pay to improve for many years. In fact, all city building games you will find on internet are pay to win or pay to improve.
I say "Pay to Improve" over "Pay to win" as there is still the pp/ resource exchange to earn premium points...