This is my 11th Casio watch and my 7th from the G-Shock family.  Like all my other Gs, the fit and finish on this watch is very nice.  Functionality-wise it's very similar to many other G-Shocks; so much so that if you've had one for a while (like the DW6600 or especially the  G9000) you'll know how pretty much everything works out of the box.

The GLS100 features: 12H/24H time, two 1000-hour 1/100th stop watches, a 24-hour countdown timer (with auto-repeat), world-time mode, 4 alarms plus a snooze alarm, 20BAR (200M) water resistance, and a low temperature LCD which is rated to -20C/-4F.  It also has an inverted display and uses two LEDs in the 5 & 7 o'clock positions to illuminate the screen.

Some of the things I like specifically about this watch.

* The band is nylon on the front and a type of suede material on the back.  It is - without a doubt - the most comfortable strap I've ever had come on a G-Shock.  It's not a thin, wimpy nylon either; it's quilted and there is some type of padding between the front & back pieces.  It gives it a very substantial feel, and it's incredibly comfortable on the wrist.

* The color (for the GLS100-5) is unique, but not garish.  I usually wear only stainless steel or black watches - I don't go for loud or wild colors.  Despite this being a brown watch, it's a very warm and unassuming brown.  Almost like something you would see associated with something military.  There is enough "bling" in the form of stainless steel screws that hold on the band & bezel, the clasp, and the grommets for each hole in the strap that the watch has some personality and isn't too drab.

* The lighting is provided by two, small LEDs at the 5 & 7 o'clock positions (there is no EL panel in this watch).  I don't know if the screen's masking is blue, or if the LEDs are blue, but when lighted the face has a definite blue color.  Surprisingly it actually works well with the brown color.  The LEDs also do a great job illuminating the entire face of the watch.

* The display is very crisp and easy to read in bright to normal light.  Because it's a reversed display it can get a little tricky to read at extreme angles or in very dim settings.  I had no problems at night in a normally lit living room, but in bed with only a 40 watt bedside light turned on, it was difficult to see without using the backlight.

* It's a very large watch (a plus in my book, maybe a minus in yours).  I'm a big guy and small watches look silly on me.  I need something in the 45mm-and-up case size so it doesn't look like I'm wearing a kid's watch.  I don't have calipers to measure this, but it's a big chunk of watch on my wrist.  It's very light, so it doesn't feel like I have an anchor weighing my arm down, but there is no mistaking this for anything less than a big watch.  It actually sits higher on my wrist than my Pathfinger PAG240, which I thought was a pretty thick watch.

* The buttons are textured and some of the biggest I've seen on a G-Shock.  I don't think I'll ever have difficulty finding or hitting them while not looking directly at the watch.  The button press is, however, completely normal (unlike some Mudman watches which can be very stiff).

So is there anything I don't like about the watch?  No, not really.  There are a couple of nits I can pick, but they don't detract enough from the awesome aspects of this watch to really bother me at all.  A couple of my nit are:

* The reverse display looks amazing in bright light, but in dim light or at extreme angles it can be difficult-to-impossible to read.  A quick glance at your watch in less-than-ideal circumstances may not be enough to get the time or check a timer.  A prolonged look may be required.

* The band attaches in what looks like adapters you'll see on other Casio watches that let you thread on a NATO watch band.  When I first looked at the GLS100 I thought it would be possible to switch out a NATO strap with the delivered hardware.  However that doesn't appear to be the case.  The nylon straps are attached to resin ends which match the watch's case.  So they're not adapters, but look to be integral to attaching the included strap to the watch case.  The plus is the spring bars are some of the largest, beefiest I've every seen on a watch; so I don't think there is any risk of ripping them out of the watch.

* The tip of the band has a leather (or faux-leather) cover.  It looks nice, but makes the end just a little wider than the band.  You have to exert more pressure or slightly bend the band to get the end through the catch.  Once the tip has passed through the band is easily adjusted.  You could look at this as a positive - if the strap every were to become unfastened it probably wouldn't just fall off your wrist before you noticed the watch flopping around.

The bottom line: If you're a fan of tough watches or Casio G-Shocks in particular, I think you'll really like this specimen.  Even though I have plenty of watches, I'm very happy I went ahead and pulled the trigger on this G!