there's good discs and bad discs, good rim brakes and bad rim brakes.
Tektro 992AG are better known as 'Oryx'. Like all cantis they will vary in how they work depending on where the bosses are set on the frame, and how they are set up. However this model of brake does not have the finest reputation, despite being very similar in design to some other brakes (like the older model Avid shorty) which work really well . On investigation I think I have found out why:
1) the OE brake blocks are not very good. Instant upgrade required.
2) the instructions say to set the canti straddle to 90 degrees included angle. If the brake is set thus so that 90 degrees is the angle when the brake is on then the braking will be OK; not brilliant, but OK. Really the straddle ought to be set lower so that the angle is nearer to nearer 120 degrees if you want real power. You can do this by fiddling with the spacers on the brake blocks (which are standard V-type ones) and/or changing the straddle for a shorter one.
3) When you do set the straddle lower, the straddle cable then fouls the slot in the RH (on front brake) arm. This forces the straddle to kink, and the springiness in the straddle then causes the brake centring to go all to cock. It is possible to set the brakes up OK but it usually requires deliberately kinking the straddle cable and/or filing a little more out of the slot, and/or adjusting the spring tension on the arms etc.
The spec of the bike doesn't indicate which brake levers are supplied; IME Tektro recommend some odd pairings which don't always work that well. Shimano road bike brakes have migrated to a new (New Super SLR, 'NSSLR') longer cable pull standard in recent years (all newly launched road STIs since 2008) and Tektro have quietly adopted this in many of their products. If the brake levers supplied are to the NSSLR standard then these cantis won't work very well, specifically they will lack power and will feel wooden.
I would use something like shimano BL-R400 or BL-R600 with those brakes.
Overall the spec of the bike isn't terrific value for money; OK it comes with tubus carriers but past that I think you are paying a fair bit for the name on the frame.
Normally an advantage to rim brakes (vs discs) is that the fork can be built springy, but a bike that is meant to carry a load might well not be like this and may have a harsh ride when unladen; you will only find out by test-riding one.
hth