Lots of people say its really really good (i agree) but others say making stuff like giant lego is stupid and too easy. Fyi it may be one of the most complex games ever to be released. Incorporating complex mathematical equasions like sin, cos, tan etc. it is VERY compex. But it can be as simple or as complex as you wish.
If Gmod gets a Bit boring for you, go onto garrysmod.org or forums.facepunchstudios.com. There you can download hundreds or even thousands of custom made mods, or you can even learn from tutorials on how to make your own mods using the simple language of LUA. And if you are complaining of little kids being pissy and minges screwing servers, JOIN A CLAN!!, Most have private and passworded servers, or even join a very well known server. Eg. Tricky's servers. Many well known servers either have many admins on all the time or RCON (Remote Console/Control), this allows an admin to see what is happening in the server and responding accordingly without being in the server itself.
Costco is closing at 6 today so ill post another post soon.