I played FFXI for years and enjoyed it. And I am enjoying playing FFXIV, the game is not flawless, what MMO is. It is still less that one month since the game was launched and all MMOs have been buggy at launch. From the reviews I have read it seems like all the reviewers are expecting FFXIV to be Warcraft and it is not(thankfully).
So lets go through the complaints:
No Auction House - Correct, this means the goldfarmers/gilsellers can't game the Auction House and create obscene levels of inflation that everyone complains about in MMOs. It would be nice if there was a signboard to list what you're selling but that wasn't in FFIX either, neither was the search function. However next update a search function for bazaars will be added.
Fatigue System - Did no one read any of the information on this game before they bought it? I knew about the fatigue system a good month before the open beta. The game is biased towards casual gamers not hard-core gamers this has never been a secret.
Interface -Bugs, big bugs -Developers say next months patch will have lots and lots of fixes.
Terrain is cookie cutter Yes the basic areas of the game have very similar terrain. Most of the zones in FFXI either large open areas or various twisty tunnels or corridors too.
Crafting - you either love it or hate it. Craft or don't craft it usually cheaper and faster to make what you need, or get your guild mates to craft for you. But the developers haev said that there will need to br crafters in the party at high level guild leves.
Server Lag -This is also a big problem -The Developers say that they are working on better load sharing on the servers. I have never played an MMO yet that did not have server load issues. Popular games have congested areas when lots of players are in the same area.
So in closing FFXIV may just not be the MMO you want to play. If you give FFXIV a few months I imagine it will get much better all around. I feel much better about paying for a 6 month sub to FFXIV at launch than I did about Age of Conan.
/BTW I ALT-TAB in FFXIV all the time. I run with Firefox, Winamp, Messenger, and Thunderbird up all the time. I have never had FFXIV lock-up or crash on me yet ALT-TABbing back and forth.