Context: I've done 5 escape games now so I have gotten more and more picky with them as time goes by. If I considered the fact that I used a Groupon, it would be 4 stars for the money, but the full price is $40.
The room was engaging and adequately challenging. I find it weird though that you are only allotted 45 mins rather than the standard 60 mins. This is actually the first escape room I did where you are only given 45 mins. However, it became clear that this was a way for the establishment to earn more money, as you can opt to "buy" more time - an additional 15 mins for 10 dollars plus unlimited hints from there on out.
My group escaped the room after purchasing the additional time/hints (because hey, Groupon deal, why not) - and mathematically that meant we would have gotten out within 60 mins and the 3 standard hints that I usually got from other escape rooms.
Summary: With Groupon, you'll be fine. If you have to pay full price, I would consider other options. The people who run this place though, are nice.