Here's the short spill on e740 from the former owner:
1. Screen. e740 has an older reflective screen. While it's OK for most people, if you hold it next to new transflective screen you wouldn't want e740. Better find e750/755
2. Wi-fi and battery life. Toshiba added a nice touch on e740, a hardware switch that allows you to turn wi-fi on/off. Battery life with wi-fi on is downright awful, expect to loose about 80% of your battery juice within an hour, even with screen brightness turned down.
3. Upgreadability. Initially, Toshiba refused e740 owners the upgrade to Windows Mobile 2003. There was a huge online campaign with people signing petitions to Toshiba. Check out Toshiba section at pocketpcpassion.com forums.
4. Expandability/form factor. This is were this PDA really shines. Somehow Toshiba managed to install both CF and SD slots at the top behind each other while keeping overall form factor fairly slim. If you ever held e310/330/350 you'd have a good idea of it's dimentions, e740 just a tad thicker. Toshiba also sold a nifty expansion module that plugs at the bottom to Hotsync port and gives you DB-15 VGA connector and a full-size USB port.
5. Firmware/battery issues. There has been a large number of users reporting that their e740 would completely drain it's battery while being turned off which would completely wipe out their files/programs. It was believed that the issue could be corrected with the latest version of their firmware. Having read this prior to purchasing e740 the first thing I did was updated the firmware. Luckily, I have not experienced any drainage/memory loss issues.
Overall, I would recommend you look for e740's newer cousin e750/755 which has a better screen and Windows Mobile 2003 and can be had for about the same price. Check out current going prices on Ebay.