I was recently able to get a hold of the two new LEGO Power Functions train sets, #7938 Passenger Train and #7939 Cargo train. As it is my son's favorite of the two, I will focus my mini-review of the Cargo Train, specifically, and the new Power Functions train system generally.
Set #7939 Cargo Train is targeted to kids aged 6-12 years old, so my son, who just turned 4 years old, is certainly far too young to have attempted building the set on his own. But the set includes a locomotive, a tank car, a flat bed with two "smart" cars (similar to #3177 Small Car), an intermodal car, two intermodal containers, an intermodal truck and trailer, a container crane, 4 minifigs and a pretty large chunk of track, which sets the playability of the set just off the charts.
As a relatively recent convert to LEGO trains (my first train set was purchased in 2005 and my first train MOC in 2006) I do not own too many other LEGO train sets. But I am reminded of one of the sets I do own, which is #4535 LEGO Express Deluxe released in 2002 for $170.00. The Cargo Train retails for $179.99, so the 9v set does have the advantage of being slightly cheaper as well as having a locomotive I much prefer (but I'm an Steam guy, anyway). But if I look at it subjectively, outside of the difference in power system, the LEGO Express Deluxe loses out quickly. The Cargo Train includes a pair of points, as well as the crane and interactive rail cars and the intermodal truck. Given the choice between the two as a playset, looking only at the sets themselves and not the power system, I would chose the Cargo Train.
The brick-built power "button" built into the cargo train's roof is just brilliant, and my son has no problems turning the train on and off when it comes time to start playing, or put the train up for the night. The Power indicator light on both the battery on top and the IR receiver behind the Engineer is easily seen, making knowing if the train is on quite simple (though this is not really the case for #7938 Passenger Train).
The new Power Functions train motor is robust and takes all the punishment my 4 year old can dish out, and still has all the power, if not more, of its 9v counterpart. It easily pulls not only the Cargo Train's full load but the two unpowered cars from the Passenger Train set and a few other cars from my collection. I've seen reports of people complaining of the PF trains slowing in corners, but I can't say this is the case for me. The only time I saw these two sets slowing is when they crossed over the new (and in my opinion ultimately faulty) "flex" track, and that was because of the loss of wheel to rail contact.
I love the Power Functions IR remote. Not only does it give me and my son the freedom of not having to be tethered to a wall outlet to power the train, but its actually easier for my son to use. The PF remote has more friction built into it compared to the 9v Regulator, which makes moving from one speed setting to the next much more tactile, and it comes with a kill button which stops the train outright, which is handy when these PF trains derail due to excess speed (which they can easily accomplish).
All in all I can highly recommend #7939 Cargo Train, as well as the its counterpart #7938 Passenger Train. You and your kids (or inner child) will have a blast playing with the sets, and the Cargo Train has enough parts and widgets to easily add raw materials to your collection if that's what you're after.
Much to the contrary of popular opinion, I still hold quite a torch for the older 9v system, and I am intimately aware of what the 9v/PF transition has meant to the AFOL train community. It took me quite a long time to warm up to the Power Functions system, but I have become an advocate for it because of the many nay-sayers, as I was, who are completely unwilling to even look at the Power Functions train system. So allow me to address just some of the benefits of the new Power Functions trains that you might not have considered:
Complex track layouts - The 9v system cannot do double-backs, wyes, and other very common rail configurations, as doing so would cause a short circuit. With all plastic track this is a non-issue, and very handy for people, like me, who do not have room for large loop layouts.
Multiple trains - the PF system allows for multiple trains running at multiple speeds on the same track. This cannot be done with 9v without a significant investment in DCC and the time to install it.
Longer trains/Stronger Motors - The new PF train motors are equal to or stronger than the 9v motors. Trains built with standard PF motors (Either the Medium or XL motors) and brick-built motor bogies are head and shoulders above 9v in terms of pulling power/tractive effort. At Brickworld 2009 a train strength competition was held and none of the 9v locomotives using non-LEGO power supplies could even come close to out-pulling the PF locomotive.
Longer/Bigger Layouts - Like it or not, electrified rails is an extremely inefficient method to powering model trains. As the electricity flows through the rails it's current drops, and the trains lose power. The further away from the power regulator, the weaker the signal, the slower the train, and eventually it becomes necessary to boost the current with either an extension cable or a second regulator. The rechargeable battery box, while expensive, offers constant current up until the point it runs out of juice - for the life of the charge your train will continue to run at peak performance.
Reliability/Replaceability - Like it or not, the motors made towards the end of the life of the 9v system were inferior to the motors made towards the beginning. Lubricants, parts, etc. were all skimped in the name of saving money. The older, more longer lasting motors are now very old. So regardless of you having an older or newer 9v motor, they're going to fail sooner than later. Power Functions motors train or otherwise are currently available, and if they fail can be replaced at retail cost. As 9v motors die the amount of usable motors will decrease, and the price of 9v will only go up. 9v rails, too, age. The metal rails will corrode and as they are used will eventually break free of the plastic track base.
Brick-Built Track/Backwards Compatibility - While 9v hold outs weep and whine about the loss of 9v, 4.5v and 12v collectors rejoice, as PF trains are not only backwards compatible with 9v rails but with 4.5v and 12v as well. You can also create realistic details, such as water pits for steam engines to take on water without stopping (as in the US), or pits for working on trains that the train can roll over under its own power. You can also create more realistic road crossings and turntables using brackets.
Other, Misc. - Without the need for electric connectivity, things like drawbridges are much more easily constructed. While it isn't my thing, customized track is much easier as well, since cutting and gluing track requires no re-wiring. The PF control system allows users to walk away from their layouts and still retain control of their trains. If the train is about to derail, or already has, no one needs to run to the other side of the layout to turn off the 9v regulator - the controls can be kept easily in a pocket.
The Power Functions train system isn't perfect, but neither was 9v. Each have their strengths and weaknesses, and I and many here at RAILBRICKS feel there is a lot of potential in combining the two. I am looking forward with open eyes and an open mind to what the future brings, and I have every reason to believe it will be great.