I would re-finish the concret surface. I have used pacific polymers (http://www.pacpoly.com/) for this and the stuff works great, you can add some silica sand to the top coat for anti skid and your done.

Ken

I don't know about refinishing the concrete. I would have to do a scratch coat to fill in the pores (its really rough) and fill the cracks, then use a polymer... but I don't think I like the idea of a "plastic" look. I guess I just don't "see" it.

Roger Cook used an interesting product on a recent "Ask This Old House" episode.  It was a basically a decking material with plastic backing that just snaps together.  It's not the real thing, but very low profile.  It is free floating so it just goes right over the cracks and such in the concrete. 

Here's a link to the video online:
http://www.thisoldhouse.com/toh/tv/ask-toh/video/0,,20567275,00.html

If the job is for a friend or family, get REAL BUSY VERY QUICKLY.  If it is for an old customer,  read sentence #1.  If for a new customer, RUN, DO NOT walk away........ FAR FAR away. this from an ex mason contractor who was in the biz for well over 30 years.

If that advice is not a possibility, there are things you must determine/consider before going any further.

1  Why did the concrete crack.
        * if it is really 2 feet thick, it could have started cracking while it was in the original cure.  The cracks could be from shrinkage
           Any time there is a thick pour, the concrete should be mixed as dry as possible as there is a lot of water t evaporate.
           You are a woodworker, so you know what happens to wood that dries too quickly.  The process is the same, but quicker, with concrete.
          From your description and the proximity to a pool, i doubt that is the problem.
2  It could be from frost heaving
        * since it is around a pool, i do not suspect frost heaving.  however, you are in Montreal.  a bit colder than my experience in Connecticut.
           If it is from frost heaving, the cause for the frost heaving must be considered. 
           Is there proper drainage.  If the problem is frost, the drainage is poor.  That will not improve by covering the cracks with masonry
           It won't improve with overlayment of any kind.  the only way to improve the problem is a major excavation.  Tear up the entire slab.
           Or as mentioned in the first paragraph >>> RUN
3  It could be from settlement.
        * I got involved with a couple of pool companies for about six months.  You would be surprised at how many corners they will cut to meet a contract price.
           They do not like to spend the $$$ to properly fill and tamp around the pool when a deck is going to be installed.
           Building codes do not specify footing depth and size specs for terraces un connected to a building structure.
           The main reason i only worked for the pools companies for six months was because i rfused to do any terracing unless the decks were to be properly supported by                    footings with proper piers for support.  I did not last for long.
I am suspicious that there was excessive shrinkage causing minor (possibly major) cracking.
Once the cracks appeared, water seeped to the soil base, froze and expanded.  FROST in Montreal!!!   How is that possible
It is most likely that the base fill settled and eventually, the concrete followed.  I would not rule out a combination of all factors noted.

no matter what the cause, i would not ouch the project without first determining the cause(s)
I suspect a major demolition should be in store and hiring a well qualified concrete mason to pour a new deck.
If that contractor tells you he is only going to replace the slab without adequate footings and piers for support, find a new contractor.
Pool work can be very tricky and can contribute to very unhappy relationships.

sorry i did not see this discussion earlier.  I hope you have not proceeded without looking into the cause factors very carefully.
Tinker

PS  I am in sort of a rush to go see GS play his first LaCross game.  I will review this again later and add if i think necessary.
T
 

I forgot to mention that another advantage to going with pavers instead of wood is that if sloped correctly and  spaces file with polymeric sand, you won't have water going through as you have with wood and penetrating the cracked concrete to the same degree.

If indeed the cracks are only surface, I would agree that an overlayment of some sorts could work.  If the cracks are more than surface, it must be determined if there is movement of the slab.  If one looks closely, there might be some breaking of the edges, sort of like you might see when sawing wood with out a chip guard or with a dull blade.  If there is any sort of chipping at the crack edges, there is movement.  If there is any disparity of the surface, such as the area to one side of a crack is slightly higher/lower than piece next to it, no amount of overlayment can be guaranteed to NOT follow suit, whether within a few months or after several winter seasons. 

After I sent my previous message, i got to thinking about the thickness of the concrete slab.  In most cases, if it was done by a reliable contractor, there would be expansion joints between sections and completely around the pool (between pool concrete and the terrace concrete). with a deck 1-1/2 to 2 feet in thickness, i would, from here, be suspicious that there is no expansion joint.  If that is the case, how long ago was the pool/terrace built?  Maybe it was done long before expansion joint was around.  I would then start checking for pool cracks as well.  From the overall description by the OP, i suspect somewhat shoddy installation. i suspect there might have been a continuous pour of pool and slab.  If that is the case, stay away from getting involved.  There will be trouble ahead. 

If there is expansion joint, (and I am still suspicious that there is none) I am wondering how the deck concrete was kept away from the pool concrete below the extent of the expansion joint. No matter, i am still very suspicious that the deck was not done by a reliable professional.  The OP had better be very careful how he proceeds. 

The overlay suggested by hockey-magnet would be fine provided the problems I have pointed out are non-existant.  Otherwise >>> beware how you proceed.  Pools and decks surrounding them can be one big PITA, even for someone with experience.  Not only a PITA for the repairer, but when such repairs become a PITA to the customer,  >>> well that does become somewhat problematic.
Tinker

Peter's reply made me think of a product I saw on one of those DIY or HGTV shows.

http://www.laplaceusa.com/chtemofl.html

A modular wood floor would be way less work than building a deck and probably easier to repair/ remove down the road.