I've always loved the G36 series - it has always been my 'go to' gun.
I have a G36 (I've had two actually, I bought one for skirmishing, and a second as a backup. I've never needed a back up though, but I gave the one I used to skirmish to a mate) but I've just bought a CM16 (it was a really good deal) from somebody - reason being is the whole customization thing. I've found that a lot of things I wanted for the G36 were either near enough always out of stock in the UK, stupidly expensive (compared to the same item, just built for a different gun such as the M series), or available cheaply on evike (but then shipping and tax ruins that). It is, however, a good, solid gun. I have the SRC one myself, but I think a decent G36 shares those traits. The collapsible stock is a plus if you're in a CQB area. Not sure what model you've been offered, but the G36C I have has a long top rail, and then three rails on the hand guard - some models don't seem to have the front rails, particularly the longer versions, because it'd be more impractical to use them I guess. So if you love your attachments, the G36C is a good model. Very, very easy to take apart. So yes, the G36 is a good starter weapon in my opinion - I am happy it was my first rifle. I am, however, selling it on the forums here (for £100 - it works absolutely flawlessly) but it seems the one you've been offered has a better deal. I've used a CA and a TM G36 - obviously the TM being the best, but I did like my SRC over the CA. It just felt nicer to use if I am honest. If you're going to buy either of those guns, then ask a load of questions and make sure that there are no problems - don't wanna get your first rifle and realise it isn't what you wanted.
Now, I bought a CM16 as I said because of the wider variety of UK stock and because you can get some pretty cool handguards and whatnot which fit different purposes. I haven't received it yet (posted yesterday), but from the pictures I've been sent, it seems to be exactly what I am looking for in terms of customization. I just wish the G36 had these options. As for a first rifle, I'd still pick the G36 over a CM16, but that is just my preference.
That was all just my opinion on the matter, but I hope it helps. If you are interested in my G36 then just shoot me a message, comes with battery, charger, couple thousand BBs and a hi cap - it is, as I said, working flawlessly and has no issues with it (mechanically or aesthetically) - it hasn't seen a skirmish yet. Also, it is UKARA compliant (not some bright colour which sticks out anywhere you go though, it has a transparent receiver which doesn't look bad at all). It has only one hi cap mag, but the standard hi caps are fairly cheap and I doubt you'd be needing too many of those anyway. They hold stupid amounts of BBs so you won't have to worry about running out of ammo. Things only start getting expensive and hard to find if you want something like an actual PMAG (not the knock offs). Well, there goes my quick sales pitch anyway, but good luck on getting your first rifle!
