Hopefully Airborne Soon is a cadet, so I would take his "experience" with a grain of salt.
As far as being a paratrooper, no it's not a guarantee, even if you are in a Battalion which has a parachute company. The spots are competitive, the physical requirements are a lot more strenuous than the basic PT step test to get in, and as the new kid on the block, you will not be the first one in line.
Also, how do you know that it's going to be something you enjoy? You may do your infantry training and find out that you're so fascinated by recconnaisance that you want to join Recce Platoon, or that you want to blow up tanks so join anti-armour platoon. You may find out that you have a pathological fear of heights and can't even jump off the mock tower, assuming you ever even got a shot at Basic Para. Right now you're putting all your eggs in one basket, and you're bound to be disappointed. You may find that you don't get the opportunity to take your para course, or you may get thrown in a jump company and find out it's not the non-stop guts'n'glory supermen that you thought it was.
If you're joining the CF because you want to be a soldier, then go right ahead. However, if the only thing you want is to be a paratrooper, then be prepared to either not get it at all, or wait a long time before the opportunity even arises to you. Aim for being the best infanteer you can be, and the rest will come (whether it's a spot in Recce Platoon, an advanced moutain ops course, or your coveted Para). If you tell your superiors that you don't want any courses or taskings other than para, then you aren't going to go very far.