I haven't experienced any pitfalls. If you upgrade, be sure to download the new v.5 maps to your memory card/s, replacing previous version maps, so the upgrades are in your Unit as well as in your computer.
Can't comment on the value. It was worth the price to me to have the most updated street, restaurant, gas station, motel, etc. info. I figure the update should be the most current version for 2 or 3 years, and the info is worth the cost, amortized over that period.