Hi Jean Michel
I've been in Dubai with my family since 2014 having relocated from Europe. My view is therefore from that perspective.
There is a complex correlation between what are the benefits, what is a Business Development Executive, and the varying levels of cost of living in Dubai.
A very good benefits package would include accommodation (see dubizzle.com especially amount payable in advance - be careful on service charges) , car (virtually impossible without one), electricity is expensive (see www.dewa.gov.ae), as is internet and phone calls. On the latter people tend to use free text services such as WhatsApp and Skype - phone calls on Skype are banned (makes sense).
If your job is development rather than sales, I would say firstly that is a little honest because Dubai is full of sales people - it is very tiresome. But the culture (if there is one with 9:1 foreigners v locals) can be one of relationship building than sales closing - depends on sector. Development therefore sounds like a job with little commission prospects in the early years and is perhaps an unreliable income source. i.e. Development and commission are not good partners - team/group bonus "yes" but not solo commission.
There are varying levels of costs of living in Dubai and varying levels of survival/existence. This is how the State can have an overwhelming number of workers from low income countries. But if you want to live as a Westerner then the cost of living rivals the best in Europe and Japan and not necessarily the same quality. These multiple levels is what contributes to stats that show Dubai as an affordable place to live. There is no such thing as cheap beer - alcohol is expensive. But if you are generally willing and have the time to shop around then finances is easier. You certainly won't starve on AED 10k per month but your life style might be different than you are used to.
A few more notes. Dubai is not a tax free country. There is an expat tax on rent; 10%. It has the largest (road) toll system in the world. Petrol is 50% less than Europe but one uses twice as much because of the air con needed. So it works out the same without the comparable European salary. 6% to 8% Sales Tax is due to implemented by 2018. There are certain restrictions on unmarried/single male accommodation. There is a good vibrant South African network in Dubai. They all seem to be doing well and this perhaps the safest place on Earth. It's quite an experience and good for 30-somethings.
Perhaps the most important thing is "do you trust your employers". Are you expected to work unreasonably once you arrive. Holding on to your passport is a good thing.
Tony