Quoted from pinballizfun:
Standard tempered is what games normally come with. It works fine and its cheap. The anti glare stuff does work but its so stupidly expensive its not worth it. You can go to a glass shop and get a regular sheet for $30 by me. anti glare is not worth 10X the cost. I'll keep it if it comes on a game. I'd never light that much money on fire for so little benefit. If you have even reasonable lighting the glare isn't an issue anyway. DMD games get a glare guard to stop the low angle reflection from the DMD. Don't light you backglass like your using it to signal aliens and you eliminate a lot of glare. Like I said it does work, it looks good when clean. Its not $300 worth of stuff you are paying to not look at.
I mostly disagree with this assessment (but not completely). If you are budget conscious and/or play games in area's with no glare, I can see why you'd take this position. I'm sure that there are some less costly things you can do to improve upon the glare but the convenience of having invisglass is a big plus.
Depending on how you play your games, invisiglass can be a must (if you want no glare), as it is in my case. The improvement in my small game room is dramatic. After getting my first game with it, I switched all of my set-up games to invisiglass.
In addition, I have not paid $300 for invisiglass for a long time. You will probably be able to find a good deal like Cointaker's Black Friday sale on two pieces that they had last year. Sure it's an added cost. If given a choice between a topper and invisiglass, I'd take the invisiglass every time even if the costs were similar. Same goes for mirrored backglasses. All of these extra's are nice bit the invisiglass actually improves the gameplay.