Yes, low self-discharge (LSD) NiMH batteries function as described. By the way, the Eneloop brand, by Sanyo, is not the only LSD battery on the market. Other LSD NiMH batteries are sometimes marketed as "hybrid," or "pre-charged" NiMH batteries. Duracell "StayCharged" and Panasonic EVOLTA batteries are other good alternatives.
Here's the basic method of why these batteries self-discharge at such a lower rate than traditional NiMH cells:
Every battery cell has an anode and a cathode. Most batteries are just several cells placed together in a series (to increase voltage), or in parallel (to increase capacity). It is common to see a combination of series and parallel to achieve specific voltages and reserve capacity.
In order to keep the cells from shorting themselves out, a separator has to be placed between the anode and cathode (negative and positive electrodes, respectively) that also allows the transport of ionic charge carriers, which are needed to complete the circuit during the passage of current.
The more efficient this separator is at isolating and separating the cathode and anode from each other, the longer it will take to self-discharge the cell.
A separator generally consists of a polymeric membrane forming a micro-porous layer. It must be chemically and electro-chemically stable towards the electrolyte and electrode materials, while remaining durable enough to withstand the high tension of battery construction. Their structure and properties considerably affect the battery performance, including the batteries energy and power densities, cycle life, and safety.
Having a thinner separator inside the cell provides the space necessary to increase its capacity, which leads to longer shelf life (requiring more time to discharge at the same rate) as well as longer application use.
The more efficient the separator is at trapping shuttle substances, the slower the battery will self-discharge. This is all evident in a study done some time ago:
The suppression mechanism of the self-discharge reaction in nickel-metal hydride batteries using a sulfonated polyolefin separator was investigated with sealed-type AA size cells. The experimental results indicate that a sulfonated polyolefin separator effectively suppresses the self-discharge reaction in nickel-metal hydride batteries by trapping nitrogen-containing redox shuttle substances. It is also found that a sulfonated polyolefin separator traps the shuttle substances as gaseous ammonia. In the experiment examining the influence of the amount of the shuttle substances on the self-discharge, the starting point of the self-discharge agreed well with the point at which the nitrogen adsorption capacity of a sulfonated polyolefin separator reached its maximum.
Suppression mechanism of the self-discharge reaction in nickel-metal hydride batteries using a sulfonated polyolefin separator, from the Research on Chemical Intermediates journal, Volume 32, Number 5 (2006), 453-459.
I hope this answers your question.
TL;DR: Yes, they last longer/self-discharge slower.