I recently went shopping for a computer and had three-and-one-half concerns (in no particular order): (1) wrist; (2) nitrox capable; (3) user-replaceable battery; and (3.5) low profile so I wouldn't feel I had a breadbox on my wrist during SI or while having a beer after the last of the day's dive. Within this framework, I wanted to pay as little as I needed to -- and of course I wanted to be sure I was focused on basic fundamentals such as readability at depth, manufacturer with prior dive computer products, etc. To date I've been a warm-water vacation diver and I didn't have any interest in springing for things like wireless air integration, digital compass, super-sophisticated download capabilties, etc. -- basically a simple, wearable, computer. The user-replacebale battery became one of the defining requirements in my search.
I ended up selecting the Oceainc Geo (same as Aeris Manta) and used it for a dozen+ dives in Belize recently. Worked very well. The manual isn't the most well written, but it provides enough to familiarize oneself with the functions and display screens. Couldn't really play with the dive mode screens until a dive, but when I did on the first dive it was intuitive and easy. The display was clear and easy to read (I was in tropical waters) and the buttons easy to control (no gloves). Encountered one warning on low NDL time and the alarm warning was quieter than others' computers' warnings I had heard on the dive but loud enough to get my attention; also experienced one "fast ascent" warning and again was not overbearing but enough to attract attention. The dive log / history function was adequate after the dive (I didn't spring for the download-to-computer capabilities so have no sense of the nature of the desktop software for dive profiles). The computer's profile over-all is not much more than a sports watch.
I'll dive Monterey soon; hope I have no issues with visibility / readability of the comp (really have no expectation of same) or with operating buttons with gloves (we'll see). And I figured (and continue to figure) when making the purchase that if I ever wanted a more complex computer I'd have the Geo as a backup. So end result is that I feel it was money well-spent and would recommend it to others looking for a straightforward and very economical wrist computer based on my limited experience with it thus far.