it all depends really. I did mine whilst it's been on the floor in my garage, which has definite advantages, however, a lot of things made it more difficult, and some things went well which could've been difficult. If you're doing it by leaning over the radiator, then you might have the following hitches, dependent on how nicely the previous person to do it copper slipped up all the bolts etc
1) getting the viscous fan off - can be a pain in the arse - apparently
2) getting the crank pulley off - can be a pain in the arse too. Getting the bolt off is just the beginning
3) getting the bolts off, especially at the top right where the water travels in to the block. I rounded the very top right bolt off, and then spent ages trying to get it out by welding nuts on to it. eventually I had to take off the entire timing case, not just the cover, and I had to actually snap this bolt off and spend ages smacking the shank out of the timing case where it had seized absolutely solid
4) the crank belt pulley (behind main crank damper pulley) can be a bugger to get off too
5) if you get the newer style of tensioner pulley, then use a shorter bolt, or you'll snap the bolt in the block, and might have to take it all off again to weld a nut on to get it out again
6) I stripped the threads in a few of the timing lid holes, and had to helicoil them. I'd get an m8 helicoil kit (got mine for about £12, and I'd pay that for each insert that I've actually used because they're possibly the greatest things ever!
compared to all of that, actually doing the belt and tensioning it etc is an absolute piece of cake, and I know that when I do it again in 60K, it's going to be so much easier than it was this time because I've been careful to clean all threads/shanks/holes and grease 'em up before putting it all back together
I reckon if I did it again now, and it all went really well, then I'd have it done in a couple of hours