We’ve been using the GLL-30 in various situations in the last month. So far we are impressed. 
It’s has a good compact build. The plastic and rubber casing seem to offer lots of protection. With it being so compact it will tuck nicely into you tool belt. It can also hang out of you pocket by the clamp while climbing up a ladder or scaffold. 

It has a locking pendulum which in my opinion is a must. With the flick of the only switch it unlocks and turns on the laser projecting a vertical and horizontal line. 
The clamp it comes with is very versatile, it can be attached to almost any surface with a ledge, but the unit itself can be detached and placed on a flat surface or mounted onto a tripod as well. 

The laser lines are crisp. We do have bigger laser lines for laying out kitchens but this guy is great for medium to smaller jobs. The best places we found use for it was working in tight areas like hanging shelves in a closet or cabinets in a bathroom. With the clamp we were able to hang it on some pre existing shelves and also a architrave. 
I really like the size of this laser level, you can keep it in your pouch or bag without loosing much room. It runs on 2 AA batteries that are included in the package. 

I tested out the span of the laser, at 11ft away from the wall, it will span a 15 1/2ft horizontal line and with a 9ft high wall it will cast the wall and 9ft on both floor and ceiling. It also casts out sharp bright red lines. 
Overall we really like it, if you just using a laser line for smaller to medium jobs and don’t want to break the bank the GLL 30 is definitely on to consider.