The question for new people is, what amount do these bombs reset to? For example, the 35% one is at 1.39...is this the first level? The 5th?
I'm not sure, but it goes up by a set amount on each reset (1.5x, 1.4x, etc, shows on each bomb). The next level will go up by that same multiplier and will require the full level to be completed in that amount of time. The investors from earlier levels are earlier rewarded on the first level-up, so there's not real advantage to "winning" a level early in the process rather than later. The lowest I've seen some of this start is ~.005BTC, but that also seriously limits the amount of winnings that are possible.
The advantage to winning a level early would be...to profit. If you invest in Lv.1, you can then invest in Lv.3, Lv.5, ect, rolling over all of your profit. It's important for new players to know, though, where the bombs usually end. If 1.39 is one of the first levels, then theres no point in playing because it would seem like there would be nobody on. But if it started at .005, that would make this the 15th level, meaning that the site was fairly active and people could feel comfortable investing in early levels.
I usually goes in waves as far as popularity is concerned, right now there is more activity than a usual day, but less than yesterday. I've seen a few bombs go up to ~3-4BTC and turn into "MIRV" bombs which is usually pretty profitable. I think the average for the higher % bombs is ~2-2.5BTC with the current activity, but that's based solely on my limited experience with the service. I think right now the 50% is still a decent buy and I can guarantee the 25% will go up to the next level (because I'm buying it
)