James, speaking personally, my reaction to the pictured press is ... yuck.
I would say that it would be very hard to know how much pressure you are applying, and would need constant attention to keep the pressure consistent over time.
With a lever type that has sufficient mechanical advantage, you don't necessarily have to lift a lot of weight, particularly with a design that lets you add several smaller weights rather than one big weight.
Duntov, the presses I have made were specifically designed to 1) be compact enough to stay on top of my cheese "cave" (i.e., former wine cooler), both for storage and while in use, 2) take advantage of the weights I already have on hand from a generic weight machine, and 3) not require clamping or weighting down the back to offset the weight hanging from the lever. To be sure, the results have not been as compact as a spring-type press, but they have achieved all three objectives. For me it is particularly nice that I can leave the press on top of the "cave" all the time, not having to move it around either to use it or to try to find a place to store it.
If the primary issue with space is more about storage than about use, be sure to look at the second press on the Sturdy Press site. It is ingeniously made to fold up into a compact size for storage. In use, though, it looks to be about the same size as any other lever press, and as designed requires room to hang a jug of water or some such as the weight.
Wattlebloke, you are certainly right that the simplest lever-style press (e.g., a couple of 2x4's and hinges) requires adjustment to keep the plunger vertical ... but there are a lot of still-relatively-simple designs for lever-style presses that constrain the plunger to keep it vertical -- the Sturdy Press being one such design, as well as the first of my designs that I posted earlier. (Actually, the second design that I posted does the best job of all of applying its force vertically ... but that design does NOT count as simple!)
James, one more option you might consider if you have the room for it:
http://cheeseforum.org/forum/index.php/topic,8421.msg59142.html#msg59142. Super-elegant in terms of simplicity of design and ease of construction, and as shown the mechanical advantage is adjusted simply by sliding the ram along the lever. You could make this design even more flexible by designing it to hold a weight which could slide along the top beam (like an old-fashioned doctor's scales). This would allow two variable adjustments that multiply for the final MA, potentially allowing a huge range of adjustment of pressure without ever having to change (or lift) the weight. Three potential issues kept me from adopting this design: 1) This press needs to be relatively long to get a sufficient range of adjustment - which means it would not be compact enough to live on my "cave"; 2) Even at the lowest pressure setting, there still would be quite a lot of MA at work, which would mean that the plunger would have very limited amount of vertical movement - potentially requiring a lot of re-adjustment of plunger height especially in the early stages of pressing; and 3) Adjustment of plunger height would be less-than-simple, and there would not be anything to constrain it to vertical movement. Still, I love the elegance of the design, and if I had the space, I'd be sorely tempted to see if there were an easy way to solve the other problems ....