4.5, almost a 5
#1 issue, this was obviosly designed for touch screens. They didnt tone down the size of buttons and scroll areas for the computer, so trying to do finite, quick in battle changes, upgrades, turret selection, etc is a HUGE pain, gets annoying real fast when you accidently sell, or miss click, or miss upgrade, etc etc.
#2 I like how hard it is, and only getting the rewind is a cool feature, but i hate when you get to level 28/30 and screw up, rewind and try again then mayble level 29 another issue comes up and you ruin your perfect score. You now have to play all 28 levels again, wish it had an evey 10 levels, or half way threw say 15 of 30 or 12 of 24 for example save point.
Other than those two things its really fun. WAY better than the others ive played, cool options that allow you to play YOUR WAY, you can get specialized weapons and make combos for how you want to defend, makes it more personal. I like the varied levels, the guys who come out and hide in the bushes and attack your towers, lots of new and creative things, expecially the COUNTER Attack where you go back and defend a level you have played but in a different way, makes for much longer game play without monotony.
Almost a 5, just those two issues, Its basic, but they spruced it up and made it more creative than a standard tower defens.