Opinions are cheap, tickets for illegal tint are not.
Check your local laws first.
I had my windows tinted, and paid a bit extra for the higher quality UV resistant tint. I noticed a big difference (I live in Georgia so it gets hot here in the summer). The guy who tinted my car said he has the same UV tint (I think they call it "ceramic"...no clue why) on his windshield. He has a really low tint, like 75% or something, but the UV resistance really keeps his car cool (so he claims).
He said no cop would ever check your windshield, they will only be focused on the side windows. Mine is legal in Georgia (35% I think). I passed on having the windshield tinted. $15 sunshades from Wal-Mart!