Once you fix the library, the example code works perfect, as is.LIBRARY FIX:In the .CPP file, you'll see this:byte SFE_TSL2561::writeUInt(unsigned char address, unsigned int value)NOTE however that it returns a TRUE/FALSE ... so to fix the library, just change it to this:boolean SFE_TSL2561::writeUInt(unsigned char address, unsigned int value)Once you fix this, it will compile perfectly.NOTE: Adding to or modding the .CPP & .H files throws an error on UINT32 for some strange reason, even if you update them correctly. Not going to dig into that here, but just leave them alone after the fix above, and it will compile and run fine.TESTING:Very accurate and quick. When covered, drops to 1 and when blasted with a flash light, it popped to 60-70 so it's reading very well. I adjusted my loop so I only do burst reads every minute since I have had experience with sensors getting hot used outside when polled every cycle of a loop(). I don't need immediate response time for light changes so it's perfect. Just drops shades outdoors in various places when the sun starts beating down.FYI:There's some meat to the lib so a pretty basic sketch eats up 25%/35% for me so I may have to cut that down to get it to fit with my ethernet, lcd and temp sensor libs. Really nice for this is it goes right on the I2C bus and has an address (0x39 adjustable) that does not conflict with any other defaults!LASTLY:Just be sure you are using the SDA and SCL pins in the proper locations and you are using the proper address, so you don't conflict on your I2C bus. The docs are VERY good at explaining default values and how to change them to avoid conflict. Gotta thank the team at sparkfun.com for doing such a great job on the provided docs/code. It is SUPER NICE and stress free when something works in 3 minutes!