If you are referring to PinStadium's, I have about 12 sets. When they work, they are amazing, but I have had a LOT of problems with them and there is no warranty. 1 set didn't even last a game until they malfunctioned. I would say around 50% of them no longer work properly after 6 months of use.
That being said, to answer your question more accurately, if you play in a fully lit room, the effect will be greatly diminished as they are primarily there to light the playfield, which will already be illuminated by your room's lighting. I only install them on machines where the playfield is so dark it negatively effects gameplay (is annoyingly dark). I use to buy the best model, but found that with the newer Sterns, most of the "flashers" are multifunction lights and don't work properly with PinStadiums; you end up using the GI lighting, UV flashers and maybe 1-2 of the coloured flashers. I only buy the lesser model now that just does the GI and UV. (I always play in the dark.)
So, depending on the game, it may be better or worse and depending on the ambient light of the room, it may be better or worse. If you always play with the room lights on, I don't think it would be worth the money.
