They do not have the infamous oil burning issue and they are generally reliable engines. The 2GR-FE engine tend to develop leaks (Valve cover gasket, timing cover). Make sure you check them. 

The V6 engine is generally very reliable, and it has a lot of power.

What is there to watch out for? Here's what I found online:

• The VVT system is supplied by a rubber hose, it can burst and the engine will get destroyed. (can be upgraded to metal)
• The Ignition system is mediocre, like so many other Toyotas of the time coils don't last much.
• The water pump fails pretty much on every one of these overtime. (although less frequent, the alternator is also meh).
• The VVT system is weak causing rattling at startup and the solenoids are of low quality.
• Less common but, The fuel system is mediocre, solenoids can get clogged and cause low performance.

Overall, it's a very good dependable engine that can last many hundreds of thousands miles,

There's just a few things you want to watch out for - but it's just as good as modern engines get.