Gamespot must have been high when reviewing this game!
To start with, there is a great new race that fits the picture quite well. The barbarians have always been one of the trademark races in the Heroes universe and finally they make their return in Heroes V. The race does not use magic, but instead their heroes have warcries which might not be as useful as real spells, but they supplement well another novelty to the game - barbarians' blood rage. Blood rage is like a meter with levels to all barbarian creatures. They gain blood rage points when attacking and killing and they lose points when waiting, defending or dying. Once they go up a level, their stats are increased. It works quite well though it puts you always on the offensive when playing with the orcs which makes some fights a bit harder than they should be. The alternative is to move your units forward and backwards, one square at a time, which shifts you further back the ATB, putting you in a less favourable position compared to just waiting and frankly, it is just stupid.
Another great idea is the return of set items from Shadow of Death. Old artefacts now form sets. Wearing some of the artifacts give you extra bonuses to the effects artefacts already have. Wearing the whole set gives you even more extras which often are unique and cannot be provided by anything else.
The third major addition is that all races have been added a second upgrade to all their creatures. Second-upgrade creatures are roughly as tough as first-upgrade creatures and one must choose between the second or the first upgrade. And choices are not always obvious - a second-upgrade Vampire has greatly increased stats, but it looses it vampirism ability; a second-upgrade Rakshasa attacks all nearby enemies, but it looses the no retaliation ability. You have to trade. Fortunately, second-upgrade creatures come from the same upgraded buildings and you can always switch units between first and second upgrade... for a price.
Some old creatures have been changed as well. Thanes, for example, no longer have the overpowered stormstrike ability when upgraded. Instead, they get a flamestrike ability with 15% chance to be activated that produces a arc-like flamewave, damaging units behind. Regular Djins now cast only defensive spells while upgraded ones cast only offensive ones, etc.
Apart from those, there are other small additions that make the game more interesting or easy to play. There are new spells in all schools. Some of them are plain dull like the wasp nest summoning, but others are neat (vampirism). There are new skills and abilities. Sacrificial altars from Heroes 3 have returned where good races sacrifice artefacts and evil ones sacrifice units for experience. (If I recall right, Gamespot states that you can only sacrifice units which is a mistake.) Furthermore, there is one tiny interface improvement which, IMO, makes a huge difference - the small icon on top of your castle picture in the adventure map interface now shows if you can build something or not and additionally it shows when you have constructed all buildings in a city. This makes managing cities in the later stages of the game on big maps much easier and faster. Touching details like this leaves a really nice impression.
All this is combined in a really nice single-player campaign, divided in several parts. The campaign is much better than Hammers of Fate or the original Heroes V with interesting levels with many varied objectives and nice twists. Unfortunately, this campaign also tends to get boring a little before it ends, just like previous Heroes V installments and at the same time, the story still feels rushed towards the end.
Overall, Tribes of the East is a great expansion pack that combines all the features of Heroes V so far (except campaigns) in a stand-alone title at a budget price. The only reason why it won't get a higher mark from me is because it is the second, and not the first expansion pack of Heroes V. I always look bad on that.