That is one big bag. and at 4.2kg, it's heavy without anything in it. I think my last long trip my bag weighed 8kg total on the way home (with souvenires and such). Contrary to what the website claims, it is definitely NOT "ideal for hiking trips."
You absolutely have got to physically go to a store, try on the bag, put some weights in it and walk around for a while. The weight should fall on your hips, not your shoulders or back. The wheels are a hassle when you're going up, down, moving quickly on unpaved roads... as is the attached daypack, throws your weight off. I perfer a messenger-style daybag, makes it easy to carry both together.
Pack light, and the wheels won't be a necesity. If this is your first time travelling, you will need a lot less than you think. Deanna (above) has got a pretty awesome blog about packing light. Another resource that is often cited on here for packing light is One Bag: http://www.onebag.com/
Good luck, and remember, whatever you don't bring you can buy on the road!