Standard class apartment located on Tsentralniy Avenue is good choice for budget travellers which with like to stay with comfort. The supermarket, public bus terminus, pharmacy, several bars and Celentano Pizzeria (great place for the fast bite) are located nearby. Apartment can accommodate 2 people (even more for extra charge). It has everything you will need during your stay - flat tv, washing machine, iron, wireless internet connection etc.
Have booked the apartment and the transport from Odessa airport to Nikolaev and back. In short, only I can say that the service was PERFECT!
The apartment looks same as on the photographs, published on this site; it's maybe small, but it is cozy. All installed equipment works fine, but don't expect that you'll have many programs on sat-TV. I asked for Internet connection and laptop for rent and this part was perfect too. The internet connection is fast, but I recommend to bring your own laptop as some programs have Russian menus, which are difficult to change to English. However, I changed Skype program to English.
One advice: order VIP service on airport when departing Odessa; next time I'll for sure order it. Dmitry, thank you so much, I enjoyed to stay in Nikolaev. In addition, I'll ask you for help me in everything else as I see that you're well organized.