G&P is often touted as being one of the best manufacturers in airsoft, that's a good price for a G&P M4 in Canada.
G&P's reputation is mainly for having nice externals and trades. The trades on that gun aren't authentic to the CF C8's btw. Their internals however are are hit and miss, for instance G&P gears have a bad rep for breaking easily. Their mechbox shells though are highly reinforced (some may say in redundant areas) and their motors are popular.
On the subject of buying guns there are two main types of buyers.
Buyer #1: I don't know and don't care to learn about "airsoft mechanics". I just want a gun that shoots well and will be reliable.
- Tends to be the newer player but also describes many veterans too.
- Needs reliable internals with externals that will suit their ascetic desires as well as facilitate their desires for attachments such as optics and flashlights.
Buyer #2: I'm going to buy this thing and tweak it just the way I like it.
- Tends strongly to be a veteran player along with the occasional new player.
- Looking at externals and is less focused on internals because externals are more expensive.
- This buyer is also prone to a scratch build.
I generally wouldn't recommend a G&P to a type 1 buyer because the gears have a high chance to need replacing soon after purchase. Also I wouldn't recommend G&P to a new player because you have only have one gun and if it goes down you're screwed till you can fix it. Gears, generally speaking being one of the most involved things to replace. As long as you're aware of the issues and ok with them, there's no reason for you not to buy the thing. It doesn't make it a bad purchase just cause some guy said so on the internet.
Basically do your homework, the more you look into different guns, through reviews and the like, the better chance you'll have to find the one "thats best for you". As long as you chose a reputable company and a gun that doesn't have all terrible reviews you won't make a "bad" choice. Just about every company out there makes an M4 and there are tones of other guns that use stanag mags, FN 2000, L85, Sig 556, Type 97, Tavor 21, XCR, 416, masada, even the G36 can be made to use them. In the end I hope I've left you with more questions than answers as the intention is to help YOU find the gun that is best for you as opposed to telling you which gun I think is best for you.
You may be interested in reading this thread. http://www.airsoftcanada.com/showthread.php?t=145365