A good expansion to Warcraft franchise, but there was more room to improve.
Burning Crusade introduces 2 new races, 4 newbie zones, a new continent to explore (though much smaller than Kalimdor/Eastern Kingdoms), dozens of dungeons, a new profession: jewelcrafting, socketed items, and Arena PvP.
2 New Races: The two new races are good additions to WoW, but they were made to balance the game's Horde/Alliance population. By giving Horde a pretty race, we will see more people playing rolling Horde than nowadays which makes the population more balanced than pre-expansion.
4 Newbie Zones: The art of these 4 newbie zones are as great as the WoW itself, Bloodmyst Isle and Azuremyst Isle have a more northern Kalimdor/Night Elvish terrain while Eversong looks very bright and beautiful (even more beautiful than Elwynn Forrest). The Ghostlands have a dark background and is more Scourge-like, but has a different new terrain to Plaguelands. All in all the new additions are great, but not necessary.
A New Continent to Explore: Outland is the place most of the people are looking forward to. It is massive, shattered and feels demonic when you enter it in Hellfire Peninsula, but the terrain isn't the same in Outland. We can see pretty looking regions in Outland as well (Zangarmarsh, Terokkar Forrest and Nagrand look relatively beautiful to Hellfire Peninsula) so there is a variety between the regions and you won't get bored. There are dozens of new quests with storylines at times and they are enough to get you solo to 70. If you aren't a solo fan, there is stuff for you as well.
New Dungeons: Blizzard has brought back Scarlet Monastery types of dungeons to Outland: Winged Dungeons. As they sound, each dungeon now has 3-4 wings which are suitable for different level types, and some of them are exclusive to raiders. The dungeons have the same great design as before, and with a lowered raid population (max 25), every class will have a very important role to play in raids. I feel that the PvE is going to be more skill-based since every mistake will now have a higher impact on the whole raid party.
Jewelcrafting: A new addition, not as great as the old professions however. It is very similar to Enchanting and it stacks with enchantments, but the jewels are only usable on socketed items. You can make rings, necks, trinkets and heads with Jewelcrafting too. Again, a good addition, but not necessary.
Flying Mounts: As they sound, they are mounts which get you high up in the sky, but only usable in Outland due to the graphical and technical problems that Azeroth has. You can get 2 types of mounts, one the normal flying mount which is gryphon (for Alliance) and wyvren (for Horde) and the armoured version of the two are the Epic flying mounts. Also there will be Netherdrakes which are the fastest flying mounts, but they are very hard to achieve (the only known way to achieve Netherdrakes at the moment is that your arena team wins an Arena Season).
Arenas: 2 new arenas are introduced in the game. Blizzard is aiming to achieve a skill-based PvP in arenas with ladders and ratings, but since there is still a high controversy about the class-balance in WoW, we should see how the arenas will turn out.
What is missing: I love the new 25-man raids. These make raiding a lot easier than before and casual games will be happy with this change. Still, I preferred more PvP love in the expansion. There are a few Outdoor PvP objectives introduced in Outland which are definitely more exciting than Plaguelands/Silithus PvP, but they don't feel very epic. I wish WoW could have something similar to RvR (in DaoC and soon WAR).
While many say that WoW has a cartoony and outdated graphics, I have to disagree. That is true that the graphic isn't high-end, and you see far less polygons on WoW than you see on for example Crylosis, but what is really important here is that first of all, lower system requirements are essential for an MMO in order to get everyone play it. Other than that, the games still looks very nice and the art is awesome. Blizzard has also planned to improve the graphics, but it won't happen anytime soon.
The sound is pretty much the same as WiW. There are new music added to the game which are, unlike WoW, not sequenced music, but are actually played by an orchestra. Nothing very special if you have played WoW.
There is a big con about fee-based MMO's. One, they require monthly fees to play. That is OK by MMO players but there is more.
Blizzard is planning to develop an expansion set per year. This makes them focus more on developing expansions rather than introducing free content patches like before. This is a big downside of expansions, where you have to pay for the content that won't be available to you otherwise, even though you are still paying the monthly fee!
Reviewer's Tilt: 7/10
Verdict: All in all, Burning Crusade is a good expansion to World of Warcraft. Some main problems of the game have solved, such as time-consuming Honour System and large-scale raids. If you love World of Warcraft, you will love it more in Outland, but if you didn't like WoW the first time you played it, don't expect a revolution from Burning Crusade.